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/ingredient/repository.go

@@ -11,7 +11,7 @@ import (
 	"github.com/jackc/pgx/v5/pgxpool"
 )
 
-// Repository handles persistence for ingredient_mappings and their translations.
+// Repository handles persistence for ingredients and their translations.
 type Repository struct {
 	pool *pgxpool.Pool
 }
@@ -21,11 +21,11 @@ func NewRepository(pool *pgxpool.Pool) *Repository {
 	return &Repository{pool: pool}
 }
 
-// Upsert inserts or updates an ingredient mapping (English canonical content).
+// Upsert inserts or updates an ingredient (English canonical content).
 // Conflict is resolved on canonical_name.
 func (r *Repository) Upsert(ctx context.Context, m *IngredientMapping) (*IngredientMapping, error) {
 	query := `
-		INSERT INTO ingredient_mappings (
+		INSERT INTO ingredients (
 			canonical_name,
 			category, default_unit,
 			calories_per_100g, protein_per_100g, fat_per_100g, carbs_per_100g, fiber_per_100g,
@@ -54,7 +54,7 @@ func (r *Repository) Upsert(ctx context.Context, m *IngredientMapping) (*Ingredi
 	return scanMappingWrite(row)
 }
 
-// GetByID returns an ingredient mapping by UUID.
+// GetByID returns an ingredient by UUID.
 // CanonicalName and aliases are resolved for the language stored in ctx.
 // Returns nil, nil if not found.
 func (r *Repository) GetByID(ctx context.Context, id string) (*IngredientMapping, error) {
@@ -68,7 +68,7 @@ func (r *Repository) GetByID(ctx context.Context, id string) (*IngredientMapping
 			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
 			im.storage_days, im.created_at, im.updated_at,
 			COALESCE(al.aliases, '[]'::json)     AS aliases
-		FROM ingredient_mappings im
+		FROM ingredients im
 		LEFT JOIN ingredient_translations it
 			ON it.ingredient_id = im.id AND it.lang = $2
 		LEFT JOIN ingredient_category_translations ict
@@ -88,7 +88,7 @@ func (r *Repository) GetByID(ctx context.Context, id string) (*IngredientMapping
 	return m, err
 }
 
-// FuzzyMatch finds the single best matching ingredient mapping for a given name.
+// FuzzyMatch finds the single best matching ingredient for a given name.
 // Searches both English and translated names for the language in ctx.
 // Returns nil, nil when no match is found.
 func (r *Repository) FuzzyMatch(ctx context.Context, name string) (*IngredientMapping, error) {
@@ -102,7 +102,7 @@ func (r *Repository) FuzzyMatch(ctx context.Context, name string) (*IngredientMa
 	return results[0], nil
 }
 
-// Search finds ingredient mappings matching the query string.
+// Search finds ingredients matching the query string.
 // Searches aliases table and translated names for the language in ctx.
 func (r *Repository) Search(ctx context.Context, query string, limit int) ([]*IngredientMapping, error) {
 	if limit <= 0 {
@@ -118,7 +118,7 @@ func (r *Repository) Search(ctx context.Context, query string, limit int) ([]*In
 			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
 			im.storage_days, im.created_at, im.updated_at,
 			COALESCE(al.aliases, '[]'::json)     AS aliases
-		FROM ingredient_mappings im
+		FROM ingredients im
 		LEFT JOIN ingredient_translations it
 			ON it.ingredient_id = im.id AND it.lang = $3
 		LEFT JOIN ingredient_category_translations ict
@@ -142,17 +142,17 @@ func (r *Repository) Search(ctx context.Context, query string, limit int) ([]*In
 
 	rows, err := r.pool.Query(ctx, q, query, limit, lang)
 	if err != nil {
-		return nil, fmt.Errorf("search ingredient_mappings: %w", err)
+		return nil, fmt.Errorf("search ingredients: %w", err)
 	}
 	defer rows.Close()
 	return collectMappingsRead(rows)
 }
 
-// Count returns the total number of ingredient mappings.
+// Count returns the total number of ingredients.
 func (r *Repository) Count(ctx context.Context) (int, error) {
 	var n int
-	if err := r.pool.QueryRow(ctx, `SELECT count(*) FROM ingredient_mappings`).Scan(&n); err != nil {
-		return 0, fmt.Errorf("count ingredient_mappings: %w", err)
+	if err := r.pool.QueryRow(ctx, `SELECT count(*) FROM ingredients`).Scan(&n); err != nil {
+		return 0, fmt.Errorf("count ingredients: %w", err)
 	}
 	return n, nil
 }
@@ -165,7 +165,7 @@ func (r *Repository) ListMissingTranslation(ctx context.Context, lang string, li
 			im.category, im.default_unit,
 			im.calories_per_100g, im.protein_per_100g, im.fat_per_100g, im.carbs_per_100g, im.fiber_per_100g,
 			im.storage_days, im.created_at, im.updated_at
-		FROM ingredient_mappings im
+		FROM ingredients im
 		WHERE NOT EXISTS (
 		    SELECT 1 FROM ingredient_translations it
 		    WHERE it.ingredient_id = im.id AND it.lang = $3