feat: add rematch functionality for recipe ingredients and enhance inventory management

- Added a new API path for rematching recipe ingredients in `api_paths.dart`.
- Implemented a manual product creation dialog in `inventory_screen.dart` to allow users to create new products directly.
- Integrated the rematch functionality in `recipe_repository.dart` to handle rematching of recipe ingredients.
- Updated the recipe detail screen to include a button for triggering the rematch process.
- Introduced a new `RecipeMatchingService` in the backend to handle ingredient matching logic.
- Added database migration to include `aiEngineEnabled` column in the User table.

Co-authored-by: Copilot <copilot@github.com>

flutter/lib/core/api/api_paths.dart

@@ -46,6 +46,7 @@ class RecipeApiPaths {
   static String unshare(int id, String username) => '/recipes/$id/share/${Uri.encodeComponent(username)}';
   static String inventoryPreview(int id) => '/recipes/$id/inventory-preview';
   static String analysis(int id) => '/recipes/$id/analysis';
+  static String rematch(int id) => '/recipes/$id/rematch';
   static const parseMarkdown = '/recipes/parse-markdown';
   static const aiSuggestions = '/recipes/ai-suggestions';
 }

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

@@ -3,8 +3,11 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../../core/api/api_error_mapper.dart';
+import '../../../core/api/api_paths.dart';
+import '../../../core/api/api_providers.dart';
 import '../../../core/l10n/l10n.dart';
 import '../../../core/ui/async_state_views.dart';
+import '../../auth/data/auth_providers.dart';
 import '../data/inventory_providers.dart';
 import 'swipeable_inventory_tile.dart';
 
@@ -19,6 +22,65 @@ class InventoryScreen extends ConsumerWidget {
     (value: 'bestBeforeDesc', label: context.l10n.inventorySortBestBeforeDesc),
   ];
 
+  Future<void> _createManualProduct(BuildContext context, WidgetRef ref) async {
+    final nameCtrl = TextEditingController();
+    final created = await showDialog<String>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Ny produkt'),
+        content: TextField(
+          controller: nameCtrl,
+          autofocus: true,
+          decoration: const InputDecoration(
+            labelText: 'Produktnamn',
+            border: OutlineInputBorder(),
+          ),
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(dialogContext),
+            child: Text(context.l10n.cancelAction),
+          ),
+          FilledButton(
+            onPressed: () {
+              final value = nameCtrl.text.trim();
+              if (value.isEmpty) return;
+              Navigator.pop(dialogContext, value);
+            },
+            child: const Text('Skapa'),
+          ),
+        ],
+      ),
+    );
+    nameCtrl.dispose();
+
+    if (created == null || created.trim().isEmpty || !context.mounted) return;
+
+    try {
+      final token = ref.read(authStateProvider).maybeWhen(
+        data: (t) => t,
+        orElse: () => null,
+          ) ??
+          await ref.read(authStateProvider.future);
+      final api = ref.read(apiClientProvider);
+      await api.postJson(
+        ProductApiPaths.createPrivate,
+        body: {'name': created.trim()},
+        token: token,
+      );
+      if (!context.mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Produkt skapad. Lägg nu till den i inventariet.')),
+      );
+      context.push('/inventory/create');
+    } catch (e) {
+      if (!context.mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        buildCopyableErrorSnackBar(context, mapErrorToUserMessage(e, context)),
+      );
+    }
+  }
+
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final location = ref.watch(inventoryLocationFilterProvider);
@@ -96,10 +158,21 @@ class InventoryScreen extends ConsumerWidget {
               Positioned(
                 right: 16,
                 bottom: 16,
-                child: FloatingActionButton.extended(
-                  onPressed: () => context.push('/inventory/create'),
-                  icon: const Icon(Icons.add),
-                  label: Text(context.l10n.addAction),
+                child: Column(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    FloatingActionButton.extended(
+                      onPressed: () => context.push('/inventory/create'),
+                      icon: const Icon(Icons.add),
+                      label: Text(context.l10n.addAction),
+                    ),
+                    const SizedBox(height: 8),
+                    FloatingActionButton.extended(
+                      onPressed: () => _createManualProduct(context, ref),
+                      icon: const Icon(Icons.add_box_outlined),
+                      label: const Text('Ny produkt'),
+                    ),
+                  ],
                 ),
               ),
             ],
@@ -129,6 +202,12 @@ class InventoryScreen extends ConsumerWidget {
                     label: Text(context.l10n.addAction),
                   ),
                   const SizedBox(height: 8),
+                  FloatingActionButton.extended(
+                    onPressed: () => _createManualProduct(context, ref),
+                    icon: const Icon(Icons.add_box_outlined),
+                    label: const Text('Ny produkt'),
+                  ),
+                  const SizedBox(height: 8),
                   FloatingActionButton.extended(
                     onPressed: () => context.go('/recipes'),
                     icon: const Icon(Icons.restaurant_menu),

flutter/lib/features/recipes/data/recipe_repository.dart

@@ -196,6 +196,28 @@ class RecipeRepository {
     }
   }
 
+  Future<RecipeAnalysis> rematchRecipeIngredients(int id,
+      {String? token}) async {
+    try {
+      final data = await _api.postJson(
+        RecipeApiPaths.rematch(id),
+        body: const {},
+        token: token,
+      );
+      if (data is! Map<String, dynamic>) {
+        throw const ApiException(
+            type: ApiErrorType.unknown, message: 'Ogiltigt svar från servern.');
+      }
+      return RecipeAnalysis.fromJson(data);
+    } on ApiException {
+      rethrow;
+    } catch (_) {
+      throw const ApiException(
+          type: ApiErrorType.network,
+          message: 'Kunde inte köra om matchning.');
+    }
+  }
+
   Future<ParsedRecipe> parseMarkdown(String markdown,
       {String? token}) async {
     try {

flutter/lib/features/recipes/presentation/recipe_detail_screen.dart

@@ -521,6 +521,29 @@ class _InventoryPreviewSectionState
     extends ConsumerState<_InventoryPreviewSection> {
   bool _loaded = false;
 
+  Future<void> _runRematch() async {
+    try {
+      final token = ref.read(authStateProvider).maybeWhen(
+        data: (t) => t,
+        orElse: () => null,
+            ) ??
+            await ref.read(authStateProvider.future);
+      await ref
+          .read(recipeRepositoryProvider)
+          .rematchRecipeIngredients(widget.recipeId, token: token);
+      ref.invalidate(recipeAnalysisProvider(widget.recipeId));
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Matchning uppdaterad')),
+      );
+    } catch (e) {
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        buildCopyableErrorSnackBar(context, mapErrorToUserMessage(e, context)),
+      );
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
@@ -538,6 +561,12 @@ class _InventoryPreviewSectionState
                 icon: const Icon(Icons.search, size: 16),
                 label: const Text('Kontrollera inventarie'),
               ),
+            if (_loaded)
+              IconButton(
+                tooltip: 'Kör om matchning',
+                icon: const Icon(Icons.auto_fix_high),
+                onPressed: _runRematch,
+              ),
             if (_loaded)
               IconButton(
                 tooltip: 'Uppdatera',