Remove info-level lint issues: avoid_dynamic_calls, use_build_context_synchronously, avoid_print, non_constant_identifier_names

- Type dynamic map accesses properly (avoid_dynamic_calls in genericMap, globalFiresBottomStats)
- Capture context before async gaps (use_build_context_synchronously in genericMap, genericMapBottom, globalFiresBottomStats)
- Replace print() with debugPrint() (avoid_print in firesApi.dart)
- Rename fireMarker function and _LayerSelectorButton to camelCase
- Rename variable FireNotifications to fireNotifications
- Fix no_default_cases in switch statements (add missing subscriptionConfirm case)
- Make FireNotification fields final, remove @immutable from YourLocation (mutable)
- Make monitoredAreas field final in _ViewModel
- Update subscribeViaApi to use copyWith instead of direct field assignment

lib/layerSelectorMapPlugin.dart

@@ -22,7 +22,7 @@ class LayerSelectorMapPluginWidget extends StatelessWidget {
                   mainAxisAlignment: MainAxisAlignment.center,
                   children: <Widget>[
                     Column(
-                      children: <Widget>[_LayerSelectorButton(store)],
+                      children: <Widget>[_layerSelectorButton(store)],
                     )
                   ],
                 ),
@@ -30,7 +30,7 @@ class LayerSelectorMapPluginWidget extends StatelessWidget {
             ]));
   }
 
-  Widget _LayerSelectorButton(Store<AppState> store) {
+  Widget _layerSelectorButton(Store<AppState> store) {
     final GlobalKey<PopupMenuButtonState<FireMapLayer>> key =
         GlobalKey<PopupMenuButtonState<FireMapLayer>>();