feat: Refactor routing and navigation structure with StatefulShellRoute

- Introduced a new function `_shellBranchIndexForPath` to determine the index of the shell branch based on the path.
- Replaced `ShellRoute` with `StatefulShellRoute.indexedStack` for better state management during navigation.
- Updated `AppShell` to handle navigation path changes and integrate with the new routing structure.
- Organized routes into `StatefulShellBranch` for better modularity and clarity.
- Enhanced admin panel functionality with improved alias management and UI updates.
- Added new methods in `ReceiptImportSessionNotifier` for managing selected items and edits more efficiently.
- Improved UI components in receipt import and admin panels for better performance and user experience.
- Added PageStorageKeys to various ListViews to maintain scroll positions across navigation.
- Documented performance goals and profiling strategies in a new PERFORMANCE.md file.

flutter/lib/core/ui/app_shell.dart

@@ -21,11 +21,13 @@ const _adminHeaderDestination = _AppDestination(
 
 class AppShell extends ConsumerWidget {
   final String location;
+  final ValueChanged<String> onNavigateToPath;
   final Widget child;
 
   const AppShell({
     super.key,
     required this.location,
+    required this.onNavigateToPath,
     required this.child,
   });
 
@@ -101,7 +103,7 @@ class AppShell extends ConsumerWidget {
     void navigateTo(int index) {
       final target = dests[index].path;
       if (target != location && context.mounted) {
-        context.go(target);
+        onNavigateToPath(target);
       }
     }
 
@@ -178,7 +180,7 @@ class AppShell extends ConsumerWidget {
               switch (value) {
                 case 'profile':
                   if (location != '/profile' && context.mounted) {
-                    context.go('/profile');
+                    onNavigateToPath('/profile');
                   }
               }
             },