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/api/api_client.dart

@@ -42,4 +42,16 @@ class ApiClient {
     final response = await _dio.delete(path);
     return response.data;
   }
+
+  /// Returns a list for endpoints that respond with a JSON array.
+  Future<List<dynamic>> getList(String path,
+      {Map<String, dynamic>? params}) async {
+    final response = await _dio.get(path, queryParameters: params);
+    return response.data as List<dynamic>;
+  }
+
+  /// Deletes a resource and expects no response body (204 No Content).
+  Future<void> deleteVoid(String path) async {
+    await _dio.delete(path);
+  }
 }