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/internal/menu/handler.go

@@ -10,10 +10,10 @@ import (
 	"sync"
 	"time"
 
+	"github.com/food-ai/backend/internal/dish"
 	"github.com/food-ai/backend/internal/gemini"
 	"github.com/food-ai/backend/internal/locale"
 	"github.com/food-ai/backend/internal/middleware"
-	"github.com/food-ai/backend/internal/savedrecipe"
 	"github.com/food-ai/backend/internal/user"
 	"github.com/go-chi/chi/v5"
 )
@@ -33,9 +33,9 @@ type ProductLister interface {
 	ListForPrompt(ctx context.Context, userID string) ([]string, error)
 }
 
-// RecipeSaver persists a single recipe and returns the stored record.
+// RecipeSaver creates a dish+recipe and returns the new recipe ID.
 type RecipeSaver interface {
-	Save(ctx context.Context, userID string, req savedrecipe.SaveRequest) (*savedrecipe.SavedRecipe, error)
+	Create(ctx context.Context, req dish.CreateRequest) (string, error)
 }
 
 // Handler handles menu and shopping-list endpoints.
@@ -136,7 +136,7 @@ func (h *Handler) GenerateMenu(w http.ResponseWriter, r *http.Request) {
 		menuReq.AvailableProducts = products
 	}
 
-	// Generate 7-day plan via OpenAI.
+	// Generate 7-day plan via Gemini.
 	days, err := h.gemini.GenerateMenu(r.Context(), menuReq)
 	if err != nil {
 		slog.Error("generate menu", "user_id", userID, "err", err)
@@ -175,7 +175,7 @@ func (h *Handler) GenerateMenu(w http.ResponseWriter, r *http.Request) {
 		days[res.day].Meals[res.meal].Recipe.ImageURL = res.imageURL
 	}
 
-	// Save all 21 recipes to saved_recipes.
+	// Persist all 21 recipes as dish+recipe rows.
 	type savedRef struct {
 		day      int
 		meal     int
@@ -184,13 +184,13 @@ func (h *Handler) GenerateMenu(w http.ResponseWriter, r *http.Request) {
 	refs := make([]savedRef, 0, len(days)*3)
 	for di, day := range days {
 		for mi, meal := range day.Meals {
-			saved, err := h.recipeSaver.Save(r.Context(), userID, recipeToSaveRequest(meal.Recipe))
+			recipeID, err := h.recipeSaver.Create(r.Context(), recipeToCreateRequest(meal.Recipe))
 			if err != nil {
 				slog.Error("save recipe for menu", "title", meal.Recipe.Title, "err", err)
 				writeError(w, http.StatusInternalServerError, "failed to save recipes")
 				return
 			}
-			refs = append(refs, savedRef{di, mi, saved.ID})
+			refs = append(refs, savedRef{di, mi, recipeID})
 		}
 	}
 
@@ -420,37 +420,25 @@ func (h *Handler) buildShoppingList(ctx context.Context, planID string) ([]Shopp
 
 	type key struct{ name, unit string }
 	totals := map[key]float64{}
-	categories := map[string]string{} // name → category (from meal_type heuristic)
 
 	for _, row := range rows {
-		var ingredients []struct {
-			Name   string  `json:"name"`
-			Amount float64 `json:"amount"`
-			Unit   string  `json:"unit"`
-		}
-		if len(row.IngredientsJSON) > 0 {
-			if err := json.Unmarshal(row.IngredientsJSON, &ingredients); err != nil {
-				continue
-			}
-		}
-		for _, ing := range ingredients {
-			k := key{strings.ToLower(strings.TrimSpace(ing.Name)), ing.Unit}
-			totals[k] += ing.Amount
-			if _, ok := categories[k.name]; !ok {
-				categories[k.name] = "other"
-			}
+		unit := ""
+		if row.UnitCode != nil {
+			unit = *row.UnitCode
 		}
+		k := key{strings.ToLower(strings.TrimSpace(row.Name)), unit}
+		totals[k] += row.Amount
 	}
 
 	items := make([]ShoppingItem, 0, len(totals))
 	for k, amount := range totals {
 		items = append(items, ShoppingItem{
-			Name:     k.name,
-			Category: categories[k.name],
-			Amount:   amount,
-			Unit:     k.unit,
-			Checked:  false,
-			InStock:  0,
+			Name:    k.name,
+			Category: "other",
+			Amount:  amount,
+			Unit:    k.unit,
+			Checked: false,
+			InStock: 0,
 		})
 	}
 	return items, nil
@@ -479,26 +467,70 @@ func buildMenuRequest(u *user.User, lang string) gemini.MenuRequest {
 	return req
 }
 
-func recipeToSaveRequest(r gemini.Recipe) savedrecipe.SaveRequest {
-	ingJSON, _ := json.Marshal(r.Ingredients)
-	stepsJSON, _ := json.Marshal(r.Steps)
-	tagsJSON, _ := json.Marshal(r.Tags)
-	nutritionJSON, _ := json.Marshal(r.Nutrition)
-	return savedrecipe.SaveRequest{
-		Title:       r.Title,
+// recipeToCreateRequest converts a Gemini recipe to a dish.CreateRequest.
+func recipeToCreateRequest(r gemini.Recipe) dish.CreateRequest {
+	cr := dish.CreateRequest{
+		Name:        r.Title,
 		Description: r.Description,
-		Cuisine:     r.Cuisine,
+		CuisineSlug: mapCuisineSlug(r.Cuisine),
+		ImageURL:    r.ImageURL,
 		Difficulty:  r.Difficulty,
 		PrepTimeMin: r.PrepTimeMin,
 		CookTimeMin: r.CookTimeMin,
 		Servings:    r.Servings,
-		ImageURL:    r.ImageURL,
-		Ingredients: ingJSON,
-		Steps:       stepsJSON,
-		Tags:        tagsJSON,
-		Nutrition:   nutritionJSON,
+		Calories:    r.Nutrition.Calories,
+		Protein:     r.Nutrition.ProteinG,
+		Fat:         r.Nutrition.FatG,
+		Carbs:       r.Nutrition.CarbsG,
 		Source:      "menu",
 	}
+	for _, ing := range r.Ingredients {
+		cr.Ingredients = append(cr.Ingredients, dish.IngredientInput{
+			Name:   ing.Name,
+			Amount: ing.Amount,
+			Unit:   ing.Unit,
+		})
+	}
+	for _, s := range r.Steps {
+		cr.Steps = append(cr.Steps, dish.StepInput{
+			Number:       s.Number,
+			Description:  s.Description,
+			TimerSeconds: s.TimerSeconds,
+		})
+	}
+	cr.Tags = append(cr.Tags, r.Tags...)
+	return cr
+}
+
+// mapCuisineSlug maps a free-form cuisine string (from Gemini) to a known slug.
+// Falls back to "other".
+func mapCuisineSlug(cuisine string) string {
+	known := map[string]string{
+		"russian":        "russian",
+		"italian":        "italian",
+		"french":         "french",
+		"chinese":        "chinese",
+		"japanese":       "japanese",
+		"korean":         "korean",
+		"mexican":        "mexican",
+		"mediterranean":  "mediterranean",
+		"indian":         "indian",
+		"thai":           "thai",
+		"american":       "american",
+		"georgian":       "georgian",
+		"spanish":        "spanish",
+		"german":         "german",
+		"middle_eastern": "middle_eastern",
+		"turkish":        "turkish",
+		"greek":          "greek",
+		"vietnamese":     "vietnamese",
+		"asian":          "other",
+		"european":       "other",
+	}
+	if s, ok := known[cuisine]; ok {
+		return s
+	}
+	return "other"
 }
 
 // resolveWeekStart parses "YYYY-WNN" or returns current week's Monday.