feat: slim meal_diary — derive name and nutrition from dish/recipe

Remove denormalized columns (name, calories, protein_g, fat_g, carbs_g)
from meal_diary. Name is now resolved via JOIN with dishes/dish_translations;
macros are computed as recipe.*_per_serving * portions at query time.

- Add dish.Repository.FindOrCreateRecipe: finds or creates a minimal recipe
  stub seeded with AI-estimated macros
- recognition/handler: resolve recipe_id synchronously per candidate;
  simplify enrichDishInBackground to translations-only
- diary/handler: accept dish_id OR name; always resolve recipe_id via
  FindOrCreateRecipe before INSERT
- diary/entity: DishID is now non-nullable string; CreateRequest drops macros
- diary/repository: ListByDate and Create use JOIN to return computed macros
- ai/types: add RecipeID field to DishCandidate
- Update tests and wire_gen accordingly

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

backend/internal/domain/diary/handler.go

@@ -17,14 +17,26 @@ type DiaryRepository interface {
 	Delete(ctx context.Context, id, userID string) error
 }
 
+// DishRepository is the subset of dish.Repository used by Handler to resolve dish IDs.
+type DishRepository interface {
+	FindOrCreate(ctx context.Context, name string) (string, bool, error)
+}
+
+// RecipeRepository is the subset of dish.Repository used by Handler to resolve recipe IDs.
+type RecipeRepository interface {
+	FindOrCreateRecipe(ctx context.Context, dishID string, calories, proteinG, fatG, carbsG float64) (string, bool, error)
+}
+
 // Handler handles diary endpoints.
 type Handler struct {
-	repo DiaryRepository
+	repo       DiaryRepository
+	dishRepo   DishRepository
+	recipeRepo RecipeRepository
 }
 
 // NewHandler creates a new Handler.
-func NewHandler(repo DiaryRepository) *Handler {
-	return &Handler{repo: repo}
+func NewHandler(repo DiaryRepository, dishRepo DishRepository, recipeRepo RecipeRepository) *Handler {
+	return &Handler{repo: repo, dishRepo: dishRepo, recipeRepo: recipeRepo}
 }
 
 // GetByDate handles GET /diary?date=YYYY-MM-DD
@@ -41,9 +53,9 @@ func (h *Handler) GetByDate(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	entries, err := h.repo.ListByDate(r.Context(), userID, date)
-	if err != nil {
-		slog.Error("list diary by date", "err", err)
+	entries, listError := h.repo.ListByDate(r.Context(), userID, date)
+	if listError != nil {
+		slog.Error("list diary by date", "err", listError)
 		writeError(w, http.StatusInternalServerError, "failed to load diary")
 		return
 	}
@@ -62,18 +74,42 @@ func (h *Handler) Create(w http.ResponseWriter, r *http.Request) {
 	}
 
 	var req CreateRequest
-	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+	if decodeError := json.NewDecoder(r.Body).Decode(&req); decodeError != nil {
 		writeError(w, http.StatusBadRequest, "invalid request body")
 		return
 	}
-	if req.Date == "" || req.Name == "" || req.MealType == "" {
-		writeError(w, http.StatusBadRequest, "date, meal_type and name are required")
+	if req.Date == "" || req.MealType == "" {
+		writeError(w, http.StatusBadRequest, "date and meal_type are required")
+		return
+	}
+	if req.DishID == nil && req.Name == "" {
+		writeError(w, http.StatusBadRequest, "dish_id or name is required")
 		return
 	}
 
-	entry, err := h.repo.Create(r.Context(), userID, req)
-	if err != nil {
-		slog.Error("create diary entry", "err", err)
+	if req.DishID == nil {
+		dishID, _, resolveError := h.dishRepo.FindOrCreate(r.Context(), req.Name)
+		if resolveError != nil {
+			slog.Error("resolve dish for diary entry", "name", req.Name, "err", resolveError)
+			writeError(w, http.StatusInternalServerError, "failed to resolve dish")
+			return
+		}
+		req.DishID = &dishID
+	}
+
+	if req.RecipeID == nil {
+		recipeID, _, recipeError := h.recipeRepo.FindOrCreateRecipe(r.Context(), *req.DishID, 0, 0, 0, 0)
+		if recipeError != nil {
+			slog.Error("find or create recipe for diary entry", "dish_id", *req.DishID, "err", recipeError)
+			writeError(w, http.StatusInternalServerError, "failed to resolve recipe")
+			return
+		}
+		req.RecipeID = &recipeID
+	}
+
+	entry, createError := h.repo.Create(r.Context(), userID, req)
+	if createError != nil {
+		slog.Error("create diary entry", "err", createError)
 		writeError(w, http.StatusInternalServerError, "failed to create diary entry")
 		return
 	}
@@ -89,12 +125,12 @@ func (h *Handler) Delete(w http.ResponseWriter, r *http.Request) {
 	}
 
 	id := chi.URLParam(r, "id")
-	if err := h.repo.Delete(r.Context(), id, userID); err != nil {
-		if err == ErrNotFound {
+	if deleteError := h.repo.Delete(r.Context(), id, userID); deleteError != nil {
+		if deleteError == ErrNotFound {
 			writeError(w, http.StatusNotFound, "diary entry not found")
 			return
 		}
-		slog.Error("delete diary entry", "err", err)
+		slog.Error("delete diary entry", "err", deleteError)
 		writeError(w, http.StatusInternalServerError, "failed to delete diary entry")
 		return
 	}