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/recipe.dart

@@ -0,0 +1,121 @@
+import 'package:json_annotation/json_annotation.dart';
+
+part 'recipe.g.dart';
+
+@JsonSerializable(explicitToJson: true)
+class Recipe {
+  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', defaultValue: '')
+  final String imageUrl;
+
+  @JsonKey(name: 'image_query', defaultValue: '')
+  final String imageQuery;
+
+  @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;
+
+  const Recipe({
+    required this.title,
+    required this.description,
+    required this.cuisine,
+    required this.difficulty,
+    required this.prepTimeMin,
+    required this.cookTimeMin,
+    required this.servings,
+    this.imageUrl = '',
+    this.imageQuery = '',
+    this.ingredients = const [],
+    this.steps = const [],
+    this.tags = const [],
+    this.nutrition,
+  });
+
+  factory Recipe.fromJson(Map<String, dynamic> json) => _$RecipeFromJson(json);
+  Map<String, dynamic> toJson() => _$RecipeToJson(this);
+}
+
+@JsonSerializable()
+class RecipeIngredient {
+  final String name;
+  final double amount;
+  final String unit;
+
+  const RecipeIngredient({
+    required this.name,
+    required this.amount,
+    required this.unit,
+  });
+
+  factory RecipeIngredient.fromJson(Map<String, dynamic> json) =>
+      _$RecipeIngredientFromJson(json);
+  Map<String, dynamic> toJson() => _$RecipeIngredientToJson(this);
+}
+
+@JsonSerializable()
+class RecipeStep {
+  final int number;
+  final String description;
+
+  @JsonKey(name: 'timer_seconds')
+  final int? timerSeconds;
+
+  const RecipeStep({
+    required this.number,
+    required this.description,
+    this.timerSeconds,
+  });
+
+  factory RecipeStep.fromJson(Map<String, dynamic> json) =>
+      _$RecipeStepFromJson(json);
+  Map<String, dynamic> toJson() => _$RecipeStepToJson(this);
+}
+
+@JsonSerializable()
+class NutritionInfo {
+  final double calories;
+
+  @JsonKey(name: 'protein_g')
+  final double proteinG;
+
+  @JsonKey(name: 'fat_g')
+  final double fatG;
+
+  @JsonKey(name: 'carbs_g')
+  final double carbsG;
+
+  @JsonKey(defaultValue: true)
+  final bool approximate;
+
+  const NutritionInfo({
+    required this.calories,
+    required this.proteinG,
+    required this.fatG,
+    required this.carbsG,
+    this.approximate = true,
+  });
+
+  factory NutritionInfo.fromJson(Map<String, dynamic> json) =>
+      _$NutritionInfoFromJson(json);
+  Map<String, dynamic> toJson() => _$NutritionInfoToJson(this);
+}