feat(clock,keyboard): alarm repeat + non-Latin keyboard alphabets

Alarm repeat (Clock Tools):
- NodePrefs::alarm_repeat_mask (weekday bitmask, struct tm::tm_wday
  convention) — new Repeat row cycles Off/Daily/Weekdays/Weekends.
  computeAlarmNextFire() scans the next 7 days for a matching weekday when
  set; evaluateAlarm() only clears alarm_on (one-shot) when the mask is
  empty, otherwise re-arms. mask==0 is byte-for-byte the original one-shot
  behaviour, so existing users see no change.

On-screen keyboard alphabets (Settings > Keyboard > Alphabet):
- KeyboardWidget reworked from single-byte ASCII cells to UTF-8 codepoints
  (insertion, backspace and T9 in-place cycling all codepoint-aware now, so a
  multi-byte character is never split) — see kbApplyCapsUtf8/kbUtf8Len/
  kbUtf8CharAt/kbUtf8LastCharBytes.
- Cyrillic, Greek and an Extended Latin set (Polish/Czech/Slovak/German/
  French/Spanish/Nordic diacritics) join the keyboard's existing #@/abc page
  cycle (Latin -> alt alphabet -> Symbols -> Latin) — no new key needed.
  NodePrefs::keyboard_alt_alphabet picks which one, if any, is active.
- Lemon font is forced on transiently inside KeyboardWidget::render() (saved
  and restored every call) whenever the alt-alphabet page is showing or
  already-typed text has non-ASCII bytes, so composing is visible even if
  Font is set to Default.
- Each script's caps-shift rule is distinct and documented in
  kbApplyCapsUtf8: flat -0x20 for ASCII/Cyrillic/Greek (with the ё/ς
  exceptions), flat -0x20 for Latin-1 (à-þ), and an adjacent-pair -1 for
  Latin Extended-A (verified against every character actually used, not a
  blanket rule for that whole Unicode block).

NodePrefs schema: two tail-appended fields this session (alarm_repeat_mask,
keyboard_alt_alphabet), SCHEMA_SENTINEL 0xC0DE001B -> 0xC0DE001D,
sizeof(NodePrefs) 2496 -> 2504 (verified via a standalone host compile).

Docs: Clock Tools' Repeat row, Settings > Keyboard > Alphabet, and the
Rooms keyboard note (no longer ASCII-only once an alphabet is enabled).

Not build-verified — no PlatformIO toolchain available this session. Caps
mappings cross-checked against Python's Unicode case tables; UTF-8 literal
bytes verified at the byte level.

docs/solo_features/clock_screen/clock_screen.md

@@ -68,11 +68,11 @@ Sensor fields show `--` when the sensor is not connected or has no data.
 
 #### Alarm
 
-A single one-shot wake alarm. Rows: **Hour**, **Minute** and **Armed**. **Enter** on Hour or Minute opens the digit editor (LEFT/RIGHT moves between the tens/units, UP/DOWN changes the digit); **Enter** on Armed toggles ON/OFF. The configured time is shown next to the **Alarm** menu row when armed, and the setting persists across reboots.
+A wake alarm with an optional repeat. Rows: **Hour**, **Minute**, **Repeat** and **Armed**. **Enter** on Hour or Minute opens the digit editor (LEFT/RIGHT moves between the tens/units, UP/DOWN changes the digit); **Enter** on Repeat cycles **Off → Daily → Weekdays → Weekends → Off**; **Enter** on Armed toggles ON/OFF. The configured time is shown next to the **Alarm** menu row when armed, and the setting persists across reboots.
 
 While an alarm is armed a bell icon signals it in two places: the top-left corner of the **Clock page** itself, and the **top status bar** of the other home pages (the status bar is hidden on the Clock page, which is why the clock face carries its own indicator). The bell is icon-only — the exact alarm time is on the **Alarm** row inside Clock Tools.
 
-The alarm is scheduled as an absolute fire instant, so it is **robust to clock re-syncs** — the mesh (every inbound packet), the companion app, GPS and the CLI can all jump the device clock at any moment. A correction that moves the clock a little still fires at the right wall-clock time; a jump that skips over the alarm time still fires (late). After firing once, the alarm disarms itself.
+The alarm is scheduled as an absolute fire instant, so it is **robust to clock re-syncs** — the mesh (every inbound packet), the companion app, GPS and the CLI can all jump the device clock at any moment. A correction that moves the clock a little still fires at the right wall-clock time; a jump that skips over the alarm time still fires (late). With **Repeat** set to Off (the default) the alarm disarms itself after firing once, same as before; with a repeat pattern set, it stays armed and re-schedules itself for the next matching day instead.
 
 The alarm only fires while the device is **awake** (it keeps running with the display off or locked). It cannot wake the device from a full **Shutdown** (the CPU and RAM are powered down), and needs a valid time source — it stays pending until the clock is synced.
 

docs/solo_features/message_screen/message_screen.md

@@ -47,9 +47,10 @@ Posting to a **room server** requires a login handshake first, so the device can
 - **Passwords are remembered across reboots.** After a successful login the password is saved on the device, so picking that room again — even after a power cycle — logs back in silently and drops you straight into the chat.
 - **A wrong or changed password self-heals.** If a saved password stops working (e.g. the server's password was changed), the failed login forgets it, so the next **Enter** prompts you to type a new one.
 - **Re-login any time** with **Hold Enter** on the room → **Login…** (see the room context menu below) — useful to switch to a new password without waiting for a failure.
+- **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 is limited to ASCII (letters, digits and common symbols); accented characters such as `ą`/`ę` can't be typed on the device. A password containing them 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/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.
 
 ---
 
@@ -105,11 +106,12 @@ A location is any `lat,lon` pair in the text — exactly what the `{loc}` placeh
 
 When **Pin to dial** is selected, a slot picker opens (Slot 1–6 showing current occupant name or "empty"). Choosing a slot that already holds another contact moves the new contact there.
 
-In the **Rooms** list the context menu instead offers a single item:
+In the **Rooms** list the context menu instead offers:
 
 | Item    | Action                                                                       |
 | ------- | ---------------------------------------------------------------------------- |
 | Login…  | Opens the password prompt to (re-)log in to this room (see Rooms — logging in) |
+| Logout  | Only shown once logged in. Forgets the saved password so the next open prompts for one again |
 
 ---
 

docs/solo_features/settings_screen/settings_screen.md

@@ -98,7 +98,8 @@ 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. |
+| 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. |
 
 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**.