fix(l2): the GPS switch no longer jumps

UiCore::setGpsEnabled() wrote the prefs to flash at once, which stalled
the loop mid-animation. It takes save = false now (default true, the L1
unchanged); the L2 marks the prefs changed and writes them on leaving
the screen, as its other switches.

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

examples/companion_radio/ui-core/UiCore.h

@@ -133,11 +133,13 @@ public:
     return i >= 0 && strcmp(_sensors->getSettingValue(i), "1") == 0;
   }
   // False when the board has no GPS.
-  bool setGpsEnabled(bool on) {
+  // save = false: the caller has the prefs written later (the L2 on leaving
+  // the screen -- a flash write mid-tap stalls the switch's animation).
+  bool setGpsEnabled(bool on, bool save = true) {
     if (gpsSettingIndex() < 0) return false;
     _sensors->setSettingValue("gps", on ? "1" : "0");
     if (_prefs) _prefs->gps_enabled = on ? 1 : 0;
-    the_mesh.savePrefs();
+    if (save) the_mesh.savePrefs();
     return true;
   }
 

examples/companion_radio/ui-lvgl/UITask.cpp

@@ -1965,7 +1965,8 @@ void UITask::refreshStatusBar() {
 }
 
 void UITask::setGps(bool on) {
-  if (!_core->setGpsEnabled(on)) { showToast("No GPS on this device"); return; }
+  if (!_core->setGpsEnabled(on, false)) { showToast("No GPS on this device"); return; }
+  prefsSave();   // written on leaving the screen, as the other switches
   refreshStatusBar();
 }