refactor: one copy of shared logic and widgets; GPS is asked for, not switched on silently

Duplicates found between the L1 and L2 frontends, and inside the L2 one:
- geo::fmtLocShare / fmtLatLon / turnDeg / isAhead (GeoUtils.h): the [LOC]
  text was built in five places, the turn angle and its "ahead" threshold in
  both navigations, coordinates by hand in nine. Tested.
- LiveShareEngine::setEnabled: live share was switched in three places.
- L1 waypoint share uses WaypointModel::shareText; Trail's "Share my pos"
  goes through UITask::quickShareMyLocation, so it now sends to a running
  live-share session as the home Map page does.
- L2 Widgets.h: switchCreate (one switch size, was four), switchRow with a
  state and callback (16 hand-wired copies), switchRowOpens (Bluetooth, WiFi,
  GPS), primaryButton (one height for Save / Measure / New area / Update).

GPS: with it off, starting the trail, live share or track back, sharing or
marking a position, or centring the map asks first ("GPS is off") on both
L1 and L2; Cancel leaves it undone. A share or a mark waits for a fresh fix
(a switched-off module may still report its last one), which also fixes the
L1 "Share my pos" sending a stale position. SOS still turns the GPS on itself.

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

examples/companion_radio/ui-lvgl/NodesView.h

@@ -294,8 +294,6 @@ static void nodeFavText() {
   if (s_nd_fav) lv_label_set_text(s_nd_fav, s_node.fav ? "Remove from favourites" : "Add to favourites");   // the star in its icon column
 }
 
-static lv_obj_t* switchRow(lv_obj_t* parent, const char* text, const char* sub, uint8_t* pref);   // below
-
 // One of the node's "Can ask for" switches; user data = its TELEM_PERM_* bit.
 static void onNodeTelemSwitch(lv_event_t* e) {
   ContactInfo* ci = the_mesh.lookupContactByPubKey(s_node.pub_key, PUB_KEY_SIZE);
@@ -366,9 +364,7 @@ void UITask::buildNode() {
     };
     uint8_t perms = contactctl::telemetry(*ci);
     for (const auto& t : T) {
-      lv_obj_t* sw = switchRow(g, t.text, t.sub, nullptr);
-      if (perms & t.bit) lv_obj_add_state(sw, LV_STATE_CHECKED);
-      lv_obj_add_event_cb(sw, onNodeTelemSwitch, LV_EVENT_VALUE_CHANGED, (void*)(uintptr_t)t.bit);
+      switchRow(g, t.text, t.sub, perms & t.bit, onNodeTelemSwitch, (void*)(uintptr_t)t.bit);
     }
   }
 
@@ -408,7 +404,7 @@ void UITask::refreshNode() {
       bearing = az;
       snprintf(dist, sizeof(dist), "%s  %d\xC2\xB0 %s", d, az, geo::bearingCardinal(az));
     }
-    snprintf(pos, sizeof(pos), "%.5f, %.5f", e.lat_e6 / 1e6, e.lon_e6 / 1e6);
+    geo::fmtLatLon(pos, sizeof(pos), e.lat_e6, e.lon_e6, true);
   } else if (!_node_from_scan) {
     snprintf(pos, sizeof(pos), "Not shared");
   }