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/shared/models/saved_recipe.dart

@@ -0,0 +1,64 @@
+import 'package:json_annotation/json_annotation.dart';
+
+import 'recipe.dart';
+
+part 'saved_recipe.g.dart';
+
+@JsonSerializable(explicitToJson: true)
+class SavedRecipe {
+  final String id;
+  final String title;
+  final String? description;
+  final String? cuisine;
+  final String? difficulty;
+
+  @JsonKey(name: 'prep_time_min')
+  final int? prepTimeMin;
+
+  @JsonKey(name: 'cook_time_min')
+  final int? cookTimeMin;
+
+  final int? servings;
+
+  @JsonKey(name: 'image_url')
+  final String? imageUrl;
+
+  @JsonKey(defaultValue: [])
+  final List<RecipeIngredient> ingredients;
+
+  @JsonKey(defaultValue: [])
+  final List<RecipeStep> steps;
+
+  @JsonKey(defaultValue: [])
+  final List<String> tags;
+
+  @JsonKey(name: 'nutrition_per_serving')
+  final NutritionInfo? nutrition;
+
+  final String source;
+
+  @JsonKey(name: 'saved_at')
+  final DateTime savedAt;
+
+  const SavedRecipe({
+    required this.id,
+    required this.title,
+    this.description,
+    this.cuisine,
+    this.difficulty,
+    this.prepTimeMin,
+    this.cookTimeMin,
+    this.servings,
+    this.imageUrl,
+    this.ingredients = const [],
+    this.steps = const [],
+    this.tags = const [],
+    this.nutrition,
+    required this.source,
+    required this.savedAt,
+  });
+
+  factory SavedRecipe.fromJson(Map<String, dynamic> json) =>
+      _$SavedRecipeFromJson(json);
+  Map<String, dynamic> toJson() => _$SavedRecipeToJson(this);
+}