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/features/recipes/recipe_provider.dart

@@ -0,0 +1,109 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../core/auth/auth_provider.dart';
+import '../../shared/models/recipe.dart';
+import '../../shared/models/saved_recipe.dart';
+import 'recipe_service.dart';
+
+// ---------------------------------------------------------------------------
+// Service provider
+// ---------------------------------------------------------------------------
+
+final recipeServiceProvider = Provider<RecipeService>((ref) {
+  return RecipeService(ref.read(apiClientProvider));
+});
+
+// ---------------------------------------------------------------------------
+// Recommendations
+// ---------------------------------------------------------------------------
+
+class RecommendationsNotifier
+    extends StateNotifier<AsyncValue<List<Recipe>>> {
+  final RecipeService _service;
+
+  RecommendationsNotifier(this._service) : super(const AsyncValue.loading()) {
+    load();
+  }
+
+  Future<void> load({int count = 5}) async {
+    state = const AsyncValue.loading();
+    state = await AsyncValue.guard(
+      () => _service.getRecommendations(count: count),
+    );
+  }
+}
+
+final recommendationsProvider = StateNotifierProvider<RecommendationsNotifier,
+    AsyncValue<List<Recipe>>>((ref) {
+  return RecommendationsNotifier(ref.read(recipeServiceProvider));
+});
+
+// ---------------------------------------------------------------------------
+// Saved recipes
+// ---------------------------------------------------------------------------
+
+class SavedRecipesNotifier
+    extends StateNotifier<AsyncValue<List<SavedRecipe>>> {
+  final RecipeService _service;
+
+  SavedRecipesNotifier(this._service) : super(const AsyncValue.loading()) {
+    load();
+  }
+
+  Future<void> load() async {
+    state = const AsyncValue.loading();
+    state = await AsyncValue.guard(() => _service.getSavedRecipes());
+  }
+
+  /// Saves [recipe] and reloads the list. Returns the saved record or null on error.
+  Future<SavedRecipe?> save(Recipe recipe) async {
+    try {
+      final saved = await _service.saveRecipe(recipe);
+      await load();
+      return saved;
+    } catch (_) {
+      return null;
+    }
+  }
+
+  /// Removes the recipe with [id] optimistically and reverts on error.
+  Future<bool> delete(String id) async {
+    final previous = state;
+    state = state.whenData(
+      (list) => list.where((r) => r.id != id).toList(),
+    );
+    try {
+      await _service.deleteSavedRecipe(id);
+      return true;
+    } catch (_) {
+      state = previous;
+      return false;
+    }
+  }
+
+  /// Returns true if any saved recipe has the same title.
+  bool isSaved(String title) {
+    return state.whenOrNull(
+          data: (list) => list.any((r) => r.title == title),
+        ) ??
+        false;
+  }
+
+  /// Returns the saved recipe ID for the given title, or null.
+  String? savedId(String title) {
+    return state.whenOrNull(
+      data: (list) {
+        try {
+          return list.firstWhere((r) => r.title == title).id;
+        } catch (_) {
+          return null;
+        }
+      },
+    );
+  }
+}
+
+final savedRecipesProvider = StateNotifierProvider<SavedRecipesNotifier,
+    AsyncValue<List<SavedRecipe>>>((ref) {
+  return SavedRecipesNotifier(ref.read(recipeServiceProvider));
+});