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>

backend/cmd/server/main.go

@@ -13,7 +13,11 @@ import (
 	"github.com/food-ai/backend/internal/auth"
 	"github.com/food-ai/backend/internal/config"
 	"github.com/food-ai/backend/internal/database"
+	"github.com/food-ai/backend/internal/gemini"
 	"github.com/food-ai/backend/internal/middleware"
+	"github.com/food-ai/backend/internal/pexels"
+	"github.com/food-ai/backend/internal/recommendation"
+	"github.com/food-ai/backend/internal/savedrecipe"
 	"github.com/food-ai/backend/internal/server"
 	"github.com/food-ai/backend/internal/user"
 )
@@ -83,8 +87,27 @@ func run() error {
 	// Auth middleware
 	authMW := middleware.Auth(&jwtAdapter{jm: jwtManager})
 
+	// External API clients
+	geminiClient := gemini.NewClient(cfg.GeminiAPIKey)
+	pexelsClient := pexels.NewClient(cfg.PexelsAPIKey)
+
+	// Recommendation domain
+	recommendationHandler := recommendation.NewHandler(geminiClient, pexelsClient, userRepo)
+
+	// Saved recipes domain
+	savedRecipeRepo := savedrecipe.NewRepository(pool)
+	savedRecipeHandler := savedrecipe.NewHandler(savedRecipeRepo)
+
 	// Router
-	router := server.NewRouter(pool, authHandler, userHandler, authMW, cfg.AllowedOrigins)
+	router := server.NewRouter(
+		pool,
+		authHandler,
+		userHandler,
+		recommendationHandler,
+		savedRecipeHandler,
+		authMW,
+		cfg.AllowedOrigins,
+	)
 
 	srv := &http.Server{
 		Addr:         fmt.Sprintf(":%d", cfg.Port),