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/dish/repository.go

@@ -98,6 +98,125 @@ func (r *Repository) List(ctx context.Context) ([]*Dish, error) {
 	return dishes, nil
 }
 
+// FindOrCreate returns the dish ID and whether it was newly created.
+// Looks up by case-insensitive name match; creates a minimal dish row if not found.
+func (r *Repository) FindOrCreate(ctx context.Context, name string) (id string, created bool, err error) {
+	queryError := r.pool.QueryRow(ctx,
+		`SELECT id FROM dishes WHERE LOWER(name) = LOWER($1) LIMIT 1`, name,
+	).Scan(&id)
+	if queryError == nil {
+		return id, false, nil
+	}
+	if !errors.Is(queryError, pgx.ErrNoRows) {
+		return "", false, fmt.Errorf("find dish %q: %w", name, queryError)
+	}
+	insertError := r.pool.QueryRow(ctx,
+		`INSERT INTO dishes (name) VALUES ($1) RETURNING id`, name,
+	).Scan(&id)
+	if insertError != nil {
+		return "", false, fmt.Errorf("create dish %q: %w", name, insertError)
+	}
+	return id, true, nil
+}
+
+// FindOrCreateRecipe returns the recipe ID for the given dish, creating a minimal stub if none exists.
+// Pass zeros for all nutrition params when no estimates are available.
+func (r *Repository) FindOrCreateRecipe(ctx context.Context, dishID string, calories, proteinG, fatG, carbsG float64) (string, bool, error) {
+	var recipeID string
+	findError := r.pool.QueryRow(ctx,
+		`SELECT id FROM recipes WHERE dish_id = $1 ORDER BY created_at ASC LIMIT 1`,
+		dishID,
+	).Scan(&recipeID)
+	if findError == nil {
+		return recipeID, false, nil
+	}
+	if !errors.Is(findError, pgx.ErrNoRows) {
+		return "", false, fmt.Errorf("find recipe for dish: %w", findError)
+	}
+
+	insertError := r.pool.QueryRow(ctx, `
+		INSERT INTO recipes (dish_id, source, servings, calories_per_serving, protein_per_serving, fat_per_serving, carbs_per_serving)
+		VALUES ($1, 'ai', 1, $2, $3, $4, $5)
+		RETURNING id`,
+		dishID, nullableFloat(calories), nullableFloat(proteinG), nullableFloat(fatG), nullableFloat(carbsG),
+	).Scan(&recipeID)
+	if insertError != nil {
+		return "", false, fmt.Errorf("create recipe stub for dish: %w", insertError)
+	}
+	return recipeID, true, nil
+}
+
+// UpsertTranslation inserts or updates the name translation for a dish in a given language.
+func (r *Repository) UpsertTranslation(ctx context.Context, dishID, lang, name string) error {
+	_, upsertError := r.pool.Exec(ctx,
+		`INSERT INTO dish_translations (dish_id, lang, name)
+		 VALUES ($1, $2, $3)
+		 ON CONFLICT (dish_id, lang) DO UPDATE SET name = EXCLUDED.name`,
+		dishID, lang, name,
+	)
+	if upsertError != nil {
+		return fmt.Errorf("upsert dish translation %s/%s: %w", dishID, lang, upsertError)
+	}
+	return nil
+}
+
+// AddRecipe inserts a recipe with its ingredients and steps for an existing dish.
+func (r *Repository) AddRecipe(ctx context.Context, dishID string, req CreateRequest) (string, error) {
+	transaction, beginError := r.pool.BeginTx(ctx, pgx.TxOptions{})
+	if beginError != nil {
+		return "", fmt.Errorf("begin tx: %w", beginError)
+	}
+	defer transaction.Rollback(ctx) //nolint:errcheck
+
+	source := req.Source
+	if source == "" {
+		source = "ai"
+	}
+
+	var recipeID string
+	insertError := transaction.QueryRow(ctx, `
+		INSERT INTO recipes (dish_id, source, difficulty, prep_time_min, cook_time_min, servings,
+			calories_per_serving, protein_per_serving, fat_per_serving, carbs_per_serving)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
+		RETURNING id`,
+		dishID, source,
+		nullableStr(req.Difficulty), nullableInt(req.PrepTimeMin), nullableInt(req.CookTimeMin), nullableInt(req.Servings),
+		nullableFloat(req.Calories), nullableFloat(req.Protein), nullableFloat(req.Fat), nullableFloat(req.Carbs),
+	).Scan(&recipeID)
+	if insertError != nil {
+		return "", fmt.Errorf("insert recipe for dish %s: %w", dishID, insertError)
+	}
+
+	for i, ingredient := range req.Ingredients {
+		if _, ingredientError := transaction.Exec(ctx, `
+			INSERT INTO recipe_ingredients (recipe_id, name, amount, unit_code, is_optional, sort_order)
+			VALUES ($1, $2, $3, NULLIF($4,''), $5, $6)`,
+			recipeID, ingredient.Name, ingredient.Amount, ingredient.Unit, ingredient.IsOptional, i,
+		); ingredientError != nil {
+			return "", fmt.Errorf("insert ingredient %d: %w", i, ingredientError)
+		}
+	}
+
+	for _, step := range req.Steps {
+		stepNumber := step.Number
+		if stepNumber <= 0 {
+			stepNumber = 1
+		}
+		if _, stepError := transaction.Exec(ctx, `
+			INSERT INTO recipe_steps (recipe_id, step_number, timer_seconds, description)
+			VALUES ($1, $2, $3, $4)`,
+			recipeID, stepNumber, step.TimerSeconds, step.Description,
+		); stepError != nil {
+			return "", fmt.Errorf("insert step %d: %w", stepNumber, stepError)
+		}
+	}
+
+	if commitError := transaction.Commit(ctx); commitError != nil {
+		return "", fmt.Errorf("commit: %w", commitError)
+	}
+	return recipeID, nil
+}
+
 // Create creates a new dish + recipe row from a CreateRequest.
 // Returns the recipe ID to be used in menu_items or user_saved_recipes.
 func (r *Repository) Create(ctx context.Context, req CreateRequest) (recipeID string, err error) {