Settings: add Home Pages visibility control

New "Home Pages" section in Settings lets the user toggle which pages
appear in the home screen carousel. Settings and Messages are always
shown; Clock, Recent, Radio, Bluetooth, Advert, GPS, Sensors, Tools
and Shutdown can each be hidden individually.

- NodePrefs: home_pages_mask uint16_t (bit per page, 0=all visible)
- HomeScreen: isPageVisible/navPage skip hidden pages; dots indicator
  counts only visible pages; enforces visible page on re-entry
- SettingsScreen: SECTION_HOME_PAGES with per-page ON/OFF toggles
- DataStore: persisted at offset 1598
- Default: all pages visible (0x01FF)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/companion_radio/MyMesh.cpp

@@ -867,6 +867,7 @@ MyMesh::MyMesh(mesh::Radio &radio, mesh::RNG &rng, mesh::RTCClock &rtc, SimpleMe
   _prefs.buzzer_volume = 4;      // max volume by default
   _prefs.ringtone_bpm_idx = 2;  // 120 bpm default
   _prefs.ringtone_len = 0;       // no custom ringtone by default
+  _prefs.home_pages_mask = 0x01FF;  // all pages visible
   _prefs.auto_off_secs = 15;    // 15 seconds auto-off by default
   _prefs.tz_offset_hours = 0;  // UTC by default
   _prefs.low_batt_mv = 3400;  // auto-shutdown at 3.4V by default