refactor(companion): tidy geo-alert / live-share; dedicated auto-pause gate

Review cleanup of the new location features:
- GeoAlertScreen + LiveShareScreen use the shared drawList() helper instead
  of hand-rolling the scroll/clamp/scrollbar maths, matching every other
  list screen.
- Extract UITask::geoAlertDistance() — one place for the target-distance
  maths, shared by the crossing evaluator and the proximity beeper.
- Geo Alert re-seeds its crossing engine after every edit, so changing the
  target/radius while armed can't fire a stale arrive/leave before exit.
- Trail auto-pause gets its own coarse movement gate
  (NodePrefs::TRAIL_AUTOPAUSE_MOVE_M = 15 m) instead of reusing the trail
  min-delta, so GPS jitter while parked doesn't keep the idle timer alive.
- Fix stale include comments.

Verified: WioTrackerL1_companion_solo_dual builds clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/companion_radio/NodePrefs.h

@@ -300,6 +300,11 @@ struct NodePrefs {  // persisted to file
     static const char* L[TRAIL_AUTOPAUSE_COUNT] = { "Off", "1m", "2m", "5m" };
     return L[idx < TRAIL_AUTOPAUSE_COUNT ? idx : 0];
   }
+  // Movement under this many metres counts as "stationary" for auto-pause.
+  // Deliberately coarser than the trail min-delta gate (and independent of it)
+  // so GPS jitter while parked doesn't keep resetting the idle timer. Engine
+  // tuning only — not persisted.
+  static const uint16_t TRAIL_AUTOPAUSE_MOVE_M = 15;
 
   // Tail sentinel written at the end of /new_prefs. Bump the low byte when
   // adding/removing/reordering fields in DataStore::savePrefs/loadPrefsInt so