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.g.dart

@@ -0,0 +1,57 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'saved_recipe.dart';
+
+// **************************************************************************
+// JsonSerializableGenerator
+// **************************************************************************
+
+SavedRecipe _$SavedRecipeFromJson(Map<String, dynamic> json) => SavedRecipe(
+  id: json['id'] as String,
+  title: json['title'] as String,
+  description: json['description'] as String?,
+  cuisine: json['cuisine'] as String?,
+  difficulty: json['difficulty'] as String?,
+  prepTimeMin: (json['prep_time_min'] as num?)?.toInt(),
+  cookTimeMin: (json['cook_time_min'] as num?)?.toInt(),
+  servings: (json['servings'] as num?)?.toInt(),
+  imageUrl: json['image_url'] as String?,
+  ingredients:
+      (json['ingredients'] as List<dynamic>?)
+          ?.map((e) => RecipeIngredient.fromJson(e as Map<String, dynamic>))
+          .toList() ??
+      [],
+  steps:
+      (json['steps'] as List<dynamic>?)
+          ?.map((e) => RecipeStep.fromJson(e as Map<String, dynamic>))
+          .toList() ??
+      [],
+  tags:
+      (json['tags'] as List<dynamic>?)?.map((e) => e as String).toList() ?? [],
+  nutrition: json['nutrition_per_serving'] == null
+      ? null
+      : NutritionInfo.fromJson(
+          json['nutrition_per_serving'] as Map<String, dynamic>,
+        ),
+  source: json['source'] as String,
+  savedAt: DateTime.parse(json['saved_at'] as String),
+);
+
+Map<String, dynamic> _$SavedRecipeToJson(SavedRecipe instance) =>
+    <String, dynamic>{
+      'id': instance.id,
+      'title': instance.title,
+      'description': instance.description,
+      'cuisine': instance.cuisine,
+      'difficulty': instance.difficulty,
+      'prep_time_min': instance.prepTimeMin,
+      'cook_time_min': instance.cookTimeMin,
+      'servings': instance.servings,
+      'image_url': instance.imageUrl,
+      'ingredients': instance.ingredients.map((e) => e.toJson()).toList(),
+      'steps': instance.steps.map((e) => e.toJson()).toList(),
+      'tags': instance.tags,
+      'nutrition_per_serving': instance.nutrition?.toJson(),
+      'source': instance.source,
+      'saved_at': instance.savedAt.toIso8601String(),
+    };