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/recipes/presentation/recipe_edit_screen.dart

@@ -152,20 +152,20 @@ class _RecipeEditScreenState extends ConsumerState<RecipeEditScreen> {
 
   String? _validateIngredients() {
     if (_ingredients.isEmpty) {
-      return 'Minst en ingrediens kravs.';
+      return 'Minst en ingrediens krävs.';
     }
     for (final ingredient in _ingredients) {
       if (ingredient.productId == null) {
-        return 'Valj produkt for alla ingredienser.';
+        return 'Välj produkt för alla ingredienser.';
       }
       final quantity = double.tryParse(
         ingredient.quantityCtrl.text.trim().replaceAll(',', '.'),
       );
       if (quantity == null || quantity < 0) {
-        return 'Ange giltig mangd for alla ingredienser.';
+        return 'Ange giltig mängd för alla ingredienser.';
       }
       if (ingredient.unit.trim().isEmpty) {
-        return 'Valj enhet for alla ingredienser.';
+        return 'Välj enhet för alla ingredienser.';
       }
     }
     return null;
@@ -225,7 +225,7 @@ class _RecipeEditScreenState extends ConsumerState<RecipeEditScreen> {
         return;
       }
       setState(() {
-        _saveError = mapErrorToUserMessage(e);
+        _saveError = mapErrorToUserMessage(e, context);
         _isSaving = false;
       });
     }
@@ -255,7 +255,7 @@ class _RecipeEditScreenState extends ConsumerState<RecipeEditScreen> {
       body: recipeAsync.when(
         loading: () => const LoadingStateView(label: 'Laddar recept...'),
         error: (error, _) => ErrorStateView(
-          message: mapErrorToUserMessage(error),
+          message: mapErrorToUserMessage(error, context),
           onRetry: () => ref.invalidate(recipeDetailProvider(widget.recipeId)),
         ),
         data: (recipe) {
@@ -321,13 +321,13 @@ class _RecipeEditScreenState extends ConsumerState<RecipeEditScreen> {
                 OutlinedButton.icon(
                   onPressed: _isSaving ? null : _addIngredient,
                   icon: const Icon(Icons.add),
-                  label: const Text('Lagg till'),
+                  label: const Text('Lägg till'),
                 ),
               ],
             ),
             const SizedBox(height: 8),
             Text(
-              'Valj produkt, mangd och enhet for varje ingrediens.',
+              'Välj produkt, mängd och enhet för varje ingrediens.',
               style: Theme.of(context).textTheme.bodySmall?.copyWith(
                   color: Theme.of(context).colorScheme.onSurfaceVariant),
             ),
@@ -341,7 +341,7 @@ class _RecipeEditScreenState extends ConsumerState<RecipeEditScreen> {
               const Card(
                 child: Padding(
                   padding: EdgeInsets.all(16),
-                  child: Text('Inga ingredienser tillagda an.'),
+                  child: Text('Inga ingredienser tillagda än.'),
                 ),
               ),
             ...List.generate(
@@ -441,14 +441,14 @@ class _RecipeEditScreenState extends ConsumerState<RecipeEditScreen> {
                   child: TextFormField(
                     controller: ingredient.quantityCtrl,
                     decoration: const InputDecoration(
-                      labelText: 'Mangd *',
+                      labelText: 'Mängd *',
                       border: OutlineInputBorder(),
                     ),
                     keyboardType:
                         const TextInputType.numberWithOptions(decimal: true),
                     validator: (value) {
                       if (value == null || value.trim().isEmpty) {
-                        return 'Ange mangd';
+                        return 'Ange mängd';
                       }
                       if (double.tryParse(value.trim().replaceAll(',', '.')) ==
                           null) {