feat(companion): core parity -- L1 sends via the core, shared telemetry, schema settings on L1

- L1's MessagesScreen sends through UiCore::sendDirectText / sendChannelText
  (its own copy of send + file + ACK tracking gone).
- ui-core/Telemetry.h: the dashboard fields (numbers, names, formats) and
  sensor readings as text, each frontend passing its Style; L2 Home, L1's
  clock page, lock screen, sensors page and GPS altitude use it.
- L2: the side button held in the first 8 s is the CLI rescue, as on L1.
- L1's repeater radio goes through rptctl.
- L1 Settings are built from SettingsSchema: short labels for small
  screens, SCHEMA_* placeholders expand to the schema's sections, one
  generic row (switch ON/OFF, bars for brightness / volume). 20 hand-written
  rows and their tables gone; L1 implements applyDisplayPrefs /
  applySoundPrefs. settings::text / step / indexOf shared with L2.
- Schema: auto-off gains 5 s; the advert sound scope reads "Direct".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/companion_radio/ui-lvgl/UITask.h

@@ -507,6 +507,7 @@ private:
   uint32_t  _next_nearby_ms = 0;
   bool      _pinging = false;
   uint32_t  _ping_started_ms = 0;
+  uint32_t  _ui_started_ms = 0;   // begin(): the side button held soon after is the CLI rescue
   lv_obj_t* _nearby_list = nullptr;
   lv_obj_t* _nearby_status = nullptr;
   lv_obj_t* _nearby_sort_lbl = nullptr;