feat: implement Iteration 1 — AI recipe recommendations

Backend:
- Add Groq LLM client (llama-3.3-70b) for recipe generation with JSON
  retry strategy (retries only on parse errors, not API errors)
- Add Pexels client for parallel photo search per recipe
- Add saved_recipes table (migration 004) with JSONB fields
- Add GET /recommendations endpoint (profile-aware prompt building)
- Add POST/GET/GET{id}/DELETE /saved-recipes CRUD endpoints
- Wire gemini, pexels, recommendation, savedrecipe packages in main.go

Flutter:
- Add Recipe, SavedRecipe models with json_serializable
- Add RecipeService (getRecommendations, getSavedRecipes, save, delete)
- Add RecommendationsNotifier and SavedRecipesNotifier (Riverpod)
- Add RecommendationsScreen with skeleton loading and refresh FAB
- Add RecipeDetailScreen (SliverAppBar, nutrition tooltip, steps with timer)
- Add SavedRecipesScreen with Dismissible swipe-to-delete and empty state
- Update RecipesScreen to TabBar (Recommendations / Saved)
- Add /recipe-detail route outside ShellRoute (no bottom nav)
- Extend ApiClient with getList() and deleteVoid()

Project:
- Add CLAUDE.md with English-only rule for comments and commit messages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/core/router/app_router.dart

@@ -8,8 +8,11 @@ import '../../features/auth/register_screen.dart';
 import '../../features/home/home_screen.dart';
 import '../../features/products/products_screen.dart';
 import '../../features/menu/menu_screen.dart';
+import '../../features/recipes/recipe_detail_screen.dart';
 import '../../features/recipes/recipes_screen.dart';
 import '../../features/profile/profile_screen.dart';
+import '../../shared/models/recipe.dart';
+import '../../shared/models/saved_recipe.dart';
 
 final routerProvider = Provider<GoRouter>((ref) {
   final authState = ref.watch(authProvider);
@@ -34,6 +37,21 @@ final routerProvider = Provider<GoRouter>((ref) {
         path: '/auth/register',
         builder: (_, __) => const RegisterScreen(),
       ),
+      // Full-screen recipe detail — shown without the bottom navigation bar.
+      GoRoute(
+        path: '/recipe-detail',
+        builder: (context, state) {
+          final extra = state.extra;
+          if (extra is Recipe) {
+            return RecipeDetailScreen(recipe: extra);
+          }
+          if (extra is SavedRecipe) {
+            return RecipeDetailScreen(saved: extra);
+          }
+          // Fallback: pop back if navigated without a valid extra.
+          return const _InvalidRoute();
+        },
+      ),
       ShellRoute(
         builder: (context, state, child) => MainShell(child: child),
         routes: [
@@ -52,6 +70,18 @@ final routerProvider = Provider<GoRouter>((ref) {
   );
 });
 
+class _InvalidRoute extends StatelessWidget {
+  const _InvalidRoute();
+
+  @override
+  Widget build(BuildContext context) {
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (context.mounted) Navigator.of(context).pop();
+    });
+    return const Scaffold(body: SizedBox.shrink());
+  }
+}
+
 class MainShell extends StatelessWidget {
   final Widget child;