feat(ui-lvgl): arrange Home's apps -- drag to move, tap to hide

Hold an app on Home (or Settings > Home apps) to arrange them: every app
is shown, hidden ones dimmed with a +; a drag drops the app into the slot
under the finger, held at a screen edge it goes to that page; a tap hides
or shows it. Settings stays shown. The order is kept in NVS (letters per
app, lower case = hidden), saved on Done or on leaving Home.

Roadmap: note the speaker-knock experiment (DAC ramp didn't help).

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

examples/companion_radio/ui-lvgl/UITask.h

@@ -43,6 +43,9 @@ public:
   // ── Navigation (called from LVGL event callbacks) ────────────────────────
   void showHome();
   void setHomePage(int page);
+  void homeEdit(bool on);   // Home's apps: drag to move, tap to hide (hold an app, or Settings > Home apps)
+  void homeAppDrop(int from, int to);
+  void homeAppToggle(int pos);
   void goHome();                   // the side button: Home's clock page
   void homeFieldSet(int slot, int field);
   void showChats();