feat(ui): on-device channel management, remote admin tool, per-language keyboards

Messages:
- Add/edit/delete channels on-device (new ChannelsView, owned by the renamed
  MessagesScreen — was QuickMsgScreen, whose name no longer matched its scope).
  Channel secret entry supports a typed passphrase (SHA-256'd, same primitive
  the library already uses for the routing hash) or a raw 32-hex-char key.
- MyMesh::setChannelLocal() factors out the setChannel/saveChannels/
  onChannelRemoved sequence previously duplicated across the two
  CMD_SET_CHANNEL branches, shared now by the BLE and on-device paths.

Tools > Admin (new):
- Log into a repeater/room server's admin account and send CLI commands,
  the on-device equivalent of the app's repeater-admin feature.
- Commands are organised into category tabs (System/Radio/Routing/Actions)
  with common get/set fields (name, radio profile, tx power, repeat, advert
  intervals, ...) plus a free-text "Custom command..." fallback for anything
  else. A field row fetches the current value, opens it pre-filled for
  editing, and sends the change — falling back to a blank editor if the
  fetch fails or times out.
- The admin password persists and self-heals exactly like room logins in
  Messages: saved on a confirmed admin-level login, forgotten on a failed
  one, left alone if merely under-privileged.
- New MyMesh::sendAdminCommand()/AbstractUITask::onAdminReply() plumbing so
  a reply reaches the UI without touching the existing BLE/app CLI-terminal
  path (queueMessage's should_display gate is untouched).

Shared TabBar.h extracted from NearbyScreen/BotScreen's independently
duplicated tab-carousel rendering (now a third consumer via Admin) — also
fixes neighbouring tabs vanishing outright when they didn't fully fit;
they now truncate with an ellipsis instead.

Keyboard: the combined "Ext.Latin" alphabet split into 8 separate,
linguistically complete per-language keyboards (Polish, Czech, Slovak,
German, French, Spanish, Portuguese, Nordic), and fixed an OLED-only bug
where tall accented glyphs overlapped the keyboard's separator line
(SH1106's Lemon-font ascent constant was 2-3px short for them).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/solo_features/message_screen/message_screen.md

@@ -50,7 +50,7 @@ Posting to a **room server** requires a login handshake first, so the device can
 - **Log out** with **Hold Enter** on a room you're currently logged into → **Logout** (only offered once logged in). Forgets the saved password on the device, so the next time you open that room it prompts for one again instead of silently reusing the old one.
 - Passwords set from the **phone app** are saved on the device too, so it can post to that room standalone after a reboot.
 
-> The on-screen keyboard's default (Latin) page is ASCII only. Typing accented or non-Latin characters — Polish/Czech/German/French diacritics, Cyrillic, or Greek — needs Settings › Keyboard › Alphabet set to the matching alphabet first; the keyboard's **#@/abc** key then cycles Latin → that alphabet → Symbols → Latin. A password containing characters outside whatever's currently enabled can still be set from the phone app — the device stores and replays it byte-for-byte.
+> The on-screen keyboard's default (Latin) page is ASCII only. Typing accented or non-Latin characters — Polish, Czech, Slovak, German, French, Spanish, Portuguese or Nordic diacritics, Cyrillic, or Greek — needs Settings › Keyboard › Alphabet set to the matching language first; the keyboard's **#@/abc** key then cycles Latin → that alphabet → Symbols → Latin. A password containing characters outside whatever's currently enabled can still be set from the phone app — the device stores and replays it byte-for-byte.
 
 ---
 
@@ -129,6 +129,24 @@ In the **Rooms** list the context menu instead offers:
 | Notif: default / OFF / ON | Per-channel notification override — **LEFT/RIGHT** to cycle           |
 | Melody: global / M1 / M2  | Per-channel melody override — **LEFT/RIGHT** to cycle                 |
 | Fav: yes / no             | Add or remove this channel from favourites — **LEFT/RIGHT** to toggle |
+| Edit                      | Opens the Add/Edit form below, pre-filled with the channel's name    |
+| Delete                    | Removes the channel immediately (no confirm prompt)                   |
+
+---
+
+### Adding / editing a channel
+
+Joining a new community channel, or creating one to share with others, no longer needs the phone app. The **Channels** list ends with a **"+ Add channel"** row — press **Enter** on it to open the form, or use **Edit** from the context menu above to change an existing channel's name or secret.
+
+| Field  | Notes                                                                                        |
+| ------ | ---------------------------------------------------------------------------------------------- |
+| Name   | Up to 31 characters                                                                            |
+| Secret | **LEFT/RIGHT** toggles between two entry modes; **Enter** opens the keyboard for whichever is selected |
+
+- **Passphrase** (default) — type any text; the device hashes it down to the channel's 16-byte secret. Easiest to agree on verbally, the same idea as a room password — two people who type the same passphrase end up on the same channel.
+- **Hex key** — type the exact 32-hex-character secret (the format used by channel QR codes, see [QR Codes](../../qr_codes.md)), for joining a channel whose precise secret you were given rather than agreeing on a new passphrase.
+
+Select **[Save]** to commit. The secret can't be redisplayed once saved (only the derived key is kept) — editing it later means typing a new passphrase or hex key, the same as re-logging into a room with a new password.
 
 ---
 

docs/solo_features/settings_screen/settings_screen.md

@@ -99,7 +99,7 @@ The **repeater** mode and its flood filters live on their own screen — see **T
 | Setting  | Options    | Notes                                                                                              |
 | -------- | ---------- | -------------------------------------------------------------------------------------------------- |
 | Layout   | ABC / T9   | On-screen keyboard style. **ABC**: an a-b-c…z grid, one key per letter (the original layout). **T9**: phone-keypad multi-tap — each key is labelled with its **digit** and a letter group (e.g. `2abc`); repeated **Enter** presses cycle through the letters and then the digit itself. Applies to whichever alphabet page is active (see Alphabet below), not just Latin. |
-| Alphabet | Latin / Cyrillic / Greek / Ext.Latin | Which extra (non-Latin) alphabet, if any, joins the keyboard's page cycle. **Latin** (default): only the Latin letters and Symbols pages, as before. Any other choice adds that alphabet's own page to the same **#@/abc** key's cycle (Latin → alphabet → Symbols → Latin) — no separate key to switch scripts. **Ext.Latin** is a curated set of Polish/Czech/Slovak/German/French/Spanish/Nordic diacritics (`ą ć ę ł ń ó ś ź ż`, `č š ž`, `ä ö ü ß`, `é è ê ë ñ`, etc.), not full Unicode coverage. **Greek** covers the 24-letter alphabet plus final sigma (`ς`) but not the tonos stress accents used in proper Modern Greek spelling. Typing in the chosen alphabet needs the **Lemon** font to actually display (Settings › Display › Font) — the keyboard forces it on temporarily while that page is open even if Font is set to Default, but received messages and everything else still follow your own Font choice. |
+| Alphabet | Latin / Cyrillic / Greek / Polish / Czech / Slovak / German / French / Spanish / Portuguese / Nordic | Which extra (non-Latin) alphabet, if any, joins the keyboard's page cycle. **Latin** (default): only the Latin letters and Symbols pages, as before. Any other choice adds that alphabet's own page to the same **#@/abc** key's cycle (Latin → alphabet → Symbols → Latin) — no separate key to switch scripts. Each Latin-diacritic language (Polish, Czech, Slovak, German, French, Spanish, Portuguese, Nordic) is its own separate page with that language's full, correct set of non-ASCII letters — e.g. Czech gets `á č ď é ě í ň ó ř š ť ú ů ý ž`, German just `ä ö ü ß`. Nordic covers `å ä æ ö ø`, shared across Danish/Norwegian/Swedish since their alphabets only differ in which of those five each one uses. **Greek** covers the 24-letter alphabet plus final sigma (`ς`) but not the tonos stress accents used in proper Modern Greek spelling. Typing in the chosen alphabet needs the **Lemon** font to actually display (Settings › Display › Font) — the keyboard forces it on temporarily while that page is open even if Font is set to Default, but received messages and everything else still follow your own Font choice. |
 
 Applies to every on-screen text field (messages, waypoint labels, room passwords, preset names). Earlier releases labelled the grid *QWERTY*; the layout has always been alphabetical, so it is now named **ABC**.
 

docs/solo_features/tools_screen/tools_screen.md

@@ -8,7 +8,7 @@
 | :-----------------------: | :-----------------------: |
 | ![](./overview_oled.png) | ![](./overview_eink.png) |
 
-The Tools screen is a hub for GPS trail recording, nearby node browsing, ringtone editing, auto-reply bot, auto-advert, live location sharing, locator, compass, clock tools (alarm / timer / stopwatch), device diagnostics, and repeater mode. Tools are grouped into collapsible **Location** / **Comms** / **System** sections — the same fold-in-place model as Settings; Tools always opens folded back to the section list. Navigate with **UP/DOWN**, press **Enter** on a section header to expand or collapse it, or on a tool to open it.
+The Tools screen is a hub for GPS trail recording, nearby node browsing, ringtone editing, auto-reply bot, auto-advert, live location sharing, locator, compass, clock tools (alarm / timer / stopwatch), device diagnostics, repeater mode, and remote admin. Tools are grouped into collapsible **Location** / **Comms** / **System** sections — the same fold-in-place model as Settings; Tools always opens folded back to the section list. Navigate with **UP/DOWN**, press **Enter** on a section header to expand or collapse it, or on a tool to open it.
 
 ---
 
@@ -509,3 +509,34 @@ The five flood filters are **opt-in** (default OFF, so a plain repeater is unaff
 While the repeater is on, a **»** indicator appears in the status bar (same blink convention as the auto-advert and trail markers) so you can tell it's relaying at a glance. Two radio settings are also overridden while relaying and restored afterwards: **Settings › Radio › Pwr save** is forced off (a repeater must listen continuously) and **Auto pwr** is forced off (a repeater holds full TX power for consistent relay reach). Both show `--` in Settings while the repeater is on.
 
 Live forwarding stats — **Forwarded**, **Pool free**, **Queue** — are shown on **Tools › Diagnostics** (this screen is config-only).
+
+---
+
+## Admin
+
+<!-- screenshot pending: Admin — target picker, command entry, reply view -->
+
+Send CLI commands to a **repeater or room server you have admin permission on** and see the text reply — the on-device equivalent of the companion app's repeater-admin feature. See [CLI Commands](../../cli_commands.md) for the full command grammar.
+
+1. **Select a node** — the list shows every repeater/room-server contact. Press **Enter** to pick one.
+2. **Log in** — type the node's **admin password** (this is the same login handshake Messages uses for room servers; a repeater's admin password is set with the `password` CLI command). If a password was already saved for this node from an earlier successful login, it retries silently instead of prompting. Only a login that comes back with **admin**-level permission unlocks the next step — anything less shows "Not admin on this node" and returns to the list.
+3. **Pick a category and a field** — a tab carousel (**LEFT/RIGHT** to switch category, **UP/DOWN** to move within it, same as Auto-Reply Bot's tabs), so common settings don't need the CLI grammar memorised:
+
+| Tab | Rows |
+| --- | ---- |
+| **System** | Name, Owner info, Admin password |
+| **Radio** | Radio (freq, bandwidth, spreading factor, coding rate), TX power |
+| **Routing** | Repeat, Advert interval, Flood advert interval, Max hops |
+| **Actions** | Reboot, Send advert, Send zero-hop advert, Sync clock, **Custom command...** |
+
+**Enter** on a row does one of three things, depending on the field:
+   - Most **System/Radio/Routing** rows first **fetch** the node's current value, then open the keyboard **pre-filled** with it to edit — submitting sends the change. If the fetch fails or times out, the keyboard still opens (blank), so the value can be set blind.
+   - **Admin password** has no fetch (there's no way to read a password back) — it opens straight to a blank keyboard.
+   - **Actions** (Reboot, Send advert, …) send immediately, no editing step.
+   - **Custom command...** (last row of Actions) opens the same free-text entry for anything not covered above — up to 160 characters, see the linked reference for the full grammar.
+4. **Read the reply** — the text reply opens in a scrollable view (**UP/DOWN** to scroll, **Cancel/Enter** to go back to the category tabs).
+
+> [!WARNING]
+> This screen can run **destructive** commands on the *remote* node — `reboot`, `erase`, a new admin password, and others. That's the same capability the phone app's repeater-admin feature already exposes, not a new risk, but double-check the value and the target before sending.
+
+**Passwords are remembered across reboots**, the same self-healing behaviour as room logins in Messages: after a successful admin login the password is saved on the device, so picking that node again — even after a power cycle — logs back in silently. If a saved password stops working (e.g. it was changed on the node), the failed login forgets it, so the next pick prompts for a new one. A correct password that just lacks admin permission is left alone — retyping the same one wouldn't change the outcome. Some commands are marked **Serial Only** in the CLI reference — those reject a remote CLI request and only work over that node's own USB serial connection.