feat(localization): Implement Swedish localization and error messages

- Added localization support for Swedish and English languages.
- Integrated localized strings for user messages in the API error mapper.
- Updated UI components to use localized strings for labels and messages.
- Ensured all error messages are context-aware and utilize the localization framework.
- Created regression test to prevent common ASCII fallbacks in Swedish UI text.

flutter/lib/features/inventory/presentation/inventory_screen.dart

@@ -14,9 +14,9 @@ class InventoryScreen extends ConsumerWidget {
   static const _locationOptions = <String>['', 'Kyl', 'Frys', 'Skafferi'];
   static const _sortOptions = <({String value, String label})>[
     (value: '', label: 'Senast tillagda'),
-    (value: 'nameAsc', label: 'Namn A-O'),
-    (value: 'bestBeforeAsc', label: 'Bast fore stigande'),
-    (value: 'bestBeforeDesc', label: 'Bast fore fallande'),
+    (value: 'nameAsc', label: 'Namn A-Ö'),
+    (value: 'bestBeforeAsc', label: 'Bäst före stigande'),
+    (value: 'bestBeforeDesc', label: 'Bäst före fallande'),
   ];
 
   @override
@@ -28,7 +28,7 @@ class InventoryScreen extends ConsumerWidget {
     return inventoryAsync.when(
       loading: () => const LoadingStateView(label: 'Laddar inventarie...'),
       error: (e, _) => ErrorStateView(
-        message: mapErrorToUserMessage(e),
+        message: mapErrorToUserMessage(e, context),
         onRetry: () => ref.invalidate(inventoryProvider),
       ),
       data: (items) {
@@ -89,7 +89,7 @@ class InventoryScreen extends ConsumerWidget {
                 padding: const EdgeInsets.only(bottom: 88),
                 children: [
                   filterSection,
-                  const EmptyStateView(title: 'Inventariet ar tomt.'),
+                  const EmptyStateView(title: 'Inventariet är tomt.'),
                 ],
               ),
               Positioned(
@@ -155,7 +155,7 @@ class _InventoryTile extends StatelessWidget {
             const Padding(
               padding: EdgeInsets.only(right: 4),
               child: Chip(
-                label: Text('Oppnad'),
+                label: Text('Öppnad'),
                 padding: EdgeInsets.zero,
                 visualDensity: VisualDensity.compact,
               ),
@@ -232,7 +232,7 @@ class _DeleteInventoryButton extends ConsumerWidget {
           } catch (error) {
             if (!context.mounted) return;
             ScaffoldMessenger.of(context).showSnackBar(
-              SnackBar(content: Text(mapErrorToUserMessage(error))),
+              SnackBar(content: Text(mapErrorToUserMessage(error, context))),
             );
           }
         },