feat: implement AI recipe suggestions; add endpoint and UI for generating suggestions based on inventory

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 const parseMarkdown = '/recipes/parse-markdown';
+  static const aiSuggestions = '/recipes/ai-suggestions';
 }
 
 class InventoryApiPaths {

flutter/lib/core/router/app_router.dart

@@ -9,6 +9,7 @@ import '../../core/auth/jwt_decoder.dart';
 import '../../features/auth/presentation/login_screen.dart';
 import '../../features/profile/presentation/profile_screen.dart';
 import '../../features/recipes/presentation/create_recipe_screen.dart';
+import '../../features/recipes/presentation/ai_recipe_suggestions_screen.dart';
 import '../../features/recipes/presentation/recipe_detail_screen.dart';
 import '../../features/recipes/presentation/recipe_edit_screen.dart';
 import '../../features/recipes/presentation/recipes_screen.dart';
@@ -67,6 +68,10 @@ final appRouterProvider = Provider<GoRouter>((ref) {
       ),
       // Detail routes — outside ShellRoute to get full-screen with back button.
       // /recipes/create must be listed before /recipes/:id to avoid conflict.
+      GoRoute(
+        path: '/recipes/ai-suggestions',
+        builder: (context, state) => const AiRecipeSuggestionsScreen(),
+      ),
       GoRoute(
         path: '/recipes/create',
         builder: (context, state) {