refactor: migrate DI to Wire, replace startup registries with on-demand DB queries

- Add google/wire; generate wire_gen.go from wire.go injector
- Move all constructor wiring out of main.go into providers.go / wire.go
- Export recognition.IngredientRepository (was unexported, blocked Wire binding)
- Delete units/cuisine/tag registry.go files (global state + unused NameFor helpers)
- Replace List handlers with NewListHandler(pool) using COALESCE SQL queries
- Remove units/cuisine/tag LoadFromDB from server startup; locale.LoadFromDB kept
  (locale.Supported is used by language middleware on every request)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/cmd/server/wire.go

@@ -0,0 +1,111 @@
+//go:build wireinject
+
+package main
+
+import (
+	"net/http"
+
+	"github.com/food-ai/backend/internal/auth"
+	"github.com/food-ai/backend/internal/config"
+	"github.com/food-ai/backend/internal/diary"
+	"github.com/food-ai/backend/internal/dish"
+	"github.com/food-ai/backend/internal/home"
+	"github.com/food-ai/backend/internal/ingredient"
+	"github.com/food-ai/backend/internal/menu"
+	"github.com/food-ai/backend/internal/middleware"
+	"github.com/food-ai/backend/internal/pexels"
+	"github.com/food-ai/backend/internal/product"
+	"github.com/food-ai/backend/internal/recipe"
+	"github.com/food-ai/backend/internal/recognition"
+	"github.com/food-ai/backend/internal/recommendation"
+	"github.com/food-ai/backend/internal/savedrecipe"
+	"github.com/food-ai/backend/internal/user"
+	"github.com/google/wire"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func initRouter(appConfig *config.Config, pool *pgxpool.Pool) (http.Handler, error) {
+	wire.Build(
+		// Config extractors
+		newGeminiAPIKey,
+		newPexelsAPIKey,
+		newJWTSecret,
+		newJWTAccessDuration,
+		newJWTRefreshDuration,
+		newAllowedOrigins,
+		newFirebaseCredentialsFile,
+
+		// Auth
+		auth.NewFirebaseAuthOrNoop,
+		newJWTManager,
+		newJWTAdapter,
+		newAuthMiddleware,
+		auth.NewService,
+		auth.NewHandler,
+
+		// User
+		user.NewRepository,
+		user.NewService,
+		user.NewHandler,
+
+		// External clients
+		newGeminiClient,
+		newPexelsClient,
+
+		// Ingredient
+		ingredient.NewRepository,
+		ingredient.NewHandler,
+
+		// Product
+		product.NewRepository,
+		product.NewHandler,
+
+		// Dish
+		dish.NewRepository,
+		dish.NewHandler,
+
+		// Recipe
+		recipe.NewRepository,
+		recipe.NewHandler,
+
+		// Saved recipes
+		savedrecipe.NewRepository,
+		savedrecipe.NewHandler,
+
+		// Menu
+		menu.NewRepository,
+		menu.NewHandler,
+
+		// Diary
+		diary.NewRepository,
+		diary.NewHandler,
+
+		// Home
+		home.NewHandler,
+
+		// Recognition & Recommendation
+		recognition.NewHandler,
+		recommendation.NewHandler,
+
+		// List handlers (DB-backed, injected into router)
+		newUnitsListHandler,
+		newCuisineListHandler,
+		newTagListHandler,
+
+		// Router
+		newRouter,
+
+		// Interface bindings
+		wire.Bind(new(user.UserRepository),              new(*user.Repository)),
+		wire.Bind(new(menu.PhotoSearcher),               new(*pexels.Client)),
+		wire.Bind(new(menu.UserLoader),                  new(*user.Repository)),
+		wire.Bind(new(menu.ProductLister),               new(*product.Repository)),
+		wire.Bind(new(menu.RecipeSaver),                 new(*dish.Repository)),
+		wire.Bind(new(recommendation.PhotoSearcher),     new(*pexels.Client)),
+		wire.Bind(new(recommendation.UserLoader),        new(*user.Repository)),
+		wire.Bind(new(recommendation.ProductLister),     new(*product.Repository)),
+		wire.Bind(new(recognition.IngredientRepository), new(*ingredient.Repository)),
+		wire.Bind(new(middleware.AccessTokenValidator),  new(*jwtAdapter)),
+	)
+	return nil, nil
+}