feat: core schema redesign — dishes, structured recipes, cuisines, tags (iteration 7)

Replaces the flat JSONB-based recipe schema with a normalized relational model:

Schema (migrations consolidated to 001_initial_schema + 002_seed_data):
- New: dishes, dish_translations, dish_tags — canonical dish catalog
- New: cuisines, tags, dish_categories with _translations tables + full seed data
- New: recipe_ingredients, recipe_steps with _translations (replaces JSONB blobs)
- New: user_saved_recipes thin bookmark (drops saved_recipes + saved_recipe_translations)
- New: product_ingredients M2M table
- recipes: now a cooking variant of a dish (dish_id FK, no title/JSONB columns)
- recipe_translations: repurposed to per-language notes only
- products: mapping_id → primary_ingredient_id
- menu_items: recipe_id FK → recipes; adds dish_id
- meal_diary: adds dish_id, recipe_id → recipes, portion_g

Backend (Go):
- New packages: internal/cuisine, internal/tag, internal/dish (registry + handler + repo)
- New GET /cuisines, GET /tags (public), GET /dishes, GET /dishes/{id}, GET /recipes/{id}
- recipe, savedrecipe, menu, diary, product, ingredient packages updated for new schema

Flutter:
- New models: Cuisine, Tag; new providers: cuisineNamesProvider, tagNamesProvider
- recipe.dart: RecipeIngredient gains unit_code + effectiveUnit getter
- saved_recipe.dart: thin model, manual fromJson, computed nutrition getter
- diary_entry.dart: adds dishId, recipeId, portionG
- recipe_detail_screen.dart: localized cuisine/tag names via providers

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

backend/cmd/server/main.go

@@ -12,8 +12,10 @@ import (
 
 	"github.com/food-ai/backend/internal/auth"
 	"github.com/food-ai/backend/internal/config"
+	"github.com/food-ai/backend/internal/cuisine"
 	"github.com/food-ai/backend/internal/database"
 	"github.com/food-ai/backend/internal/diary"
+	"github.com/food-ai/backend/internal/dish"
 	"github.com/food-ai/backend/internal/gemini"
 	"github.com/food-ai/backend/internal/home"
 	"github.com/food-ai/backend/internal/ingredient"
@@ -23,10 +25,12 @@ import (
 	"github.com/food-ai/backend/internal/units"
 	"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/server"
+	"github.com/food-ai/backend/internal/tag"
 	"github.com/food-ai/backend/internal/user"
 )
 
@@ -84,6 +88,16 @@ func run() error {
 	}
 	slog.Info("units loaded", "count", len(units.Records))
 
+	if err := cuisine.LoadFromDB(ctx, pool); err != nil {
+		return fmt.Errorf("load cuisines: %w", err)
+	}
+	slog.Info("cuisines loaded", "count", len(cuisine.Records))
+
+	if err := tag.LoadFromDB(ctx, pool); err != nil {
+		return fmt.Errorf("load tags: %w", err)
+	}
+	slog.Info("tags loaded", "count", len(tag.Records))
+
 	// Firebase auth
 	firebaseAuth, err := auth.NewFirebaseAuthOrNoop(cfg.FirebaseCredentialsFile)
 	if err != nil {
@@ -123,13 +137,21 @@ func run() error {
 	// Recommendation domain
 	recommendationHandler := recommendation.NewHandler(geminiClient, pexelsClient, userRepo, productRepo)
 
+	// Dish domain
+	dishRepo := dish.NewRepository(pool)
+	dishHandler := dish.NewHandler(dishRepo)
+
+	// Recipe domain
+	recipeRepo := recipe.NewRepository(pool)
+	recipeHandler := recipe.NewHandler(recipeRepo)
+
 	// Saved recipes domain
-	savedRecipeRepo := savedrecipe.NewRepository(pool)
+	savedRecipeRepo := savedrecipe.NewRepository(pool, dishRepo)
 	savedRecipeHandler := savedrecipe.NewHandler(savedRecipeRepo)
 
 	// Menu domain
 	menuRepo := menu.NewRepository(pool)
-	menuHandler := menu.NewHandler(menuRepo, geminiClient, pexelsClient, userRepo, productRepo, savedRecipeRepo)
+	menuHandler := menu.NewHandler(menuRepo, geminiClient, pexelsClient, userRepo, productRepo, dishRepo)
 
 	// Diary domain
 	diaryRepo := diary.NewRepository(pool)
@@ -151,6 +173,8 @@ func run() error {
 		menuHandler,
 		diaryHandler,
 		homeHandler,
+		dishHandler,
+		recipeHandler,
 		authMW,
 		cfg.AllowedOrigins,
 	)