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>

examples/companion_radio/ui-new/NearbyScreen.h

@@ -1,6 +1,7 @@
 #pragma once
 #include "../GeoUtils.h"
 #include "NavView.h"
+#include "TabBar.h"
 
 // ── Nearby Nodes ──────────────────────────────────────────────────────────────
 // One list / detail / action-menu interaction path over two sources:
@@ -692,56 +693,12 @@ class NearbyScreen : public UIScreen {
     return false;
   }
 
-  // One filter tab: short label; the active one is an inverted pill (same look as
-  // a selected row) so it reads as "you are here" in the tab strip.
-  void drawTab(DisplayDriver& display, int x, int w, const char* label, bool active) {
-    int lh = display.getLineHeight();
-    if (active) {
-      display.setColor(DisplayDriver::LIGHT);
-      display.fillRect(x, 0, w, lh + 1);
-      display.setColor(DisplayDriver::DARK);
-    } else {
-      display.setColor(DisplayDriver::LIGHT);
-    }
-    display.drawTextCentered(x + w / 2, 0, label);
-    display.setColor(DisplayDriver::LIGHT);
-  }
-
-  // Header as a circular filter tab bar: the active filter sits centred as a
-  // filled pill, neighbours fan out either side and wrap around (the tab before
-  // "All" is "Snsr", and vice-versa), matching the wrap-around LEFT/RIGHT cycle.
-  // Only whole tabs are drawn — a tab that would spill past a screen edge is
-  // skipped rather than clipped, so labels never wrap onto a second line.
+  // Header as a circular filter tab bar (shared geometry — see TabBar.h): the
+  // active filter sits centred as a filled pill, neighbours fan out either
+  // side and wrap around (the tab before "All" is "Snsr", and vice-versa),
+  // matching the wrap-around LEFT/RIGHT cycle.
   void drawFilterTabs(DisplayDriver& display) {
-    const int pad = 3, gap = 2;
-    int w[F_COUNT];
-    for (int i = 0; i < F_COUNT; i++)
-      w[i] = display.getTextWidth(FILTER_LABELS[i]) + pad * 2;
-
-    int ax = display.width() / 2 - w[_filter] / 2;   // active tab centred
-    drawTab(display, ax, w[_filter], FILTER_LABELS[_filter], true);
-
-    int lx = ax - gap;                                // next left tab's right edge
-    int rx = ax + w[_filter] + gap;                   // next right tab's left edge
-    int rx_limit = display.width() - display.menuHintWidth();  // leave room for the ≡ hint
-    bool lfit = true, rfit = true;
-    for (int k = 1; k <= F_COUNT / 2 && (lfit || rfit); k++) {
-      int li = (_filter - k + F_COUNT) % F_COUNT;
-      int ri = (_filter + k) % F_COUNT;
-      if (lfit) {
-        int x = lx - w[li];
-        if (x >= 0) { drawTab(display, x, w[li], FILTER_LABELS[li], false); lx = x - gap; }
-        else lfit = false;
-      }
-      // Skip the right side when it lands on the same tab as the left (the single
-      // opposite tab on an even count) so it isn't drawn twice.
-      if (rfit && ri != li) {
-        if (rx + w[ri] <= rx_limit) { drawTab(display, rx, w[ri], FILTER_LABELS[ri], false); rx += w[ri] + gap; }
-        else rfit = false;
-      }
-    }
-    display.setColor(DisplayDriver::LIGHT);
-    display.fillRect(0, display.headerH() - display.sepH(), display.width(), display.sepH());
+    tabbar::draw(display, FILTER_LABELS, F_COUNT, _filter, display.menuHintWidth());
     display.drawContextMenuHint(DisplayDriver::LIGHT, ctxMenuOpen());   // Nodes list has a Hold-Enter menu
   }