Add mounted guards for BuildContext use across async gaps

lib/widgets/add_node_sheet.dart

@@ -89,7 +89,8 @@ class _AddNodeSheetState extends State<AddNodeSheet> {
   void _checkSubmissionGuideAndProceed(BuildContext context, AppState appState, LocalizationService locService) async {
     // Check if user has seen the submission guide
     final hasSeenGuide = await ChangelogService().hasSeenSubmissionGuide();
-    
+    if (!context.mounted) return;
+
     if (!hasSeenGuide) {
       // Show submission guide dialog first
       final shouldProceed = await showDialog<bool>(
@@ -97,13 +98,14 @@ class _AddNodeSheetState extends State<AddNodeSheet> {
         barrierDismissible: false,
         builder: (context) => const SubmissionGuideDialog(),
       );
-      
+      if (!context.mounted) return;
+
       // If user canceled the submission guide, don't proceed with submission
       if (shouldProceed != true) {
         return;
       }
     }
-    
+
     // Now proceed with proximity check
     _checkProximityOnly(context, appState, locService);
   }

lib/widgets/advanced_edit_options_sheet.dart

@@ -185,6 +185,7 @@ class AdvancedEditOptionsSheet extends StatelessWidget {
     }
     
     // No custom scheme or app launch failed - redirect to app store
+    if (!context.mounted) return;
     await _redirectToAppStore(context, editor);
   }
 

lib/widgets/download_area_dialog.dart

@@ -264,8 +264,9 @@ class _DownloadAreaDialogState extends State<DownloadAreaDialog> {
                 try {
                   final id = DateTime.now().toIso8601String().replaceAll(':', '-');
                   final appDocDir = await OfflineAreaService().getOfflineAreaDir();
+                  if (!context.mounted) return;
                   final dir = "${appDocDir.path}/$id";
-                  
+
                   // Get current tile provider info
                   final appState = context.read<AppState>();
                   final selectedProvider = appState.selectedTileProvider;
@@ -292,6 +293,7 @@ class _DownloadAreaDialogState extends State<DownloadAreaDialog> {
                     builder: (context) => const DownloadStartedDialog(),
                   );
                 } catch (e) {
+                  if (!context.mounted) return;
                   Navigator.pop(context);
                   showDialog(
                     context: context,

lib/widgets/edit_node_sheet.dart

@@ -92,7 +92,8 @@ class _EditNodeSheetState extends State<EditNodeSheet> {
   void _checkSubmissionGuideAndProceed(BuildContext context, AppState appState, LocalizationService locService) async {
     // Check if user has seen the submission guide
     final hasSeenGuide = await ChangelogService().hasSeenSubmissionGuide();
-    
+    if (!context.mounted) return;
+
     if (!hasSeenGuide) {
       // Show submission guide dialog first
       final shouldProceed = await showDialog<bool>(
@@ -100,13 +101,14 @@ class _EditNodeSheetState extends State<EditNodeSheet> {
         barrierDismissible: false,
         builder: (context) => const SubmissionGuideDialog(),
       );
-      
+      if (!context.mounted) return;
+
       // If user canceled the submission guide, don't proceed with submission
       if (shouldProceed != true) {
         return;
       }
     }
-    
+
     // Now proceed with proximity check
     _checkProximityOnly(context, appState, locService);
   }

lib/widgets/nuclear_reset_dialog.dart

@@ -96,7 +96,8 @@ class NuclearResetDialog extends StatelessWidget {
     
     // Clear all app data
     await NuclearResetService.clearEverything();
-    
+
+    if (!context.mounted) return;
     // Show non-dismissible dialog
     await showDialog(
       context: context,