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>

client/lib/shared/models/saved_recipe.g.dart

@@ -1,57 +1,3 @@
 // GENERATED CODE - DO NOT MODIFY BY HAND
-
-part of 'saved_recipe.dart';
-
-// **************************************************************************
-// JsonSerializableGenerator
-// **************************************************************************
-
-SavedRecipe _$SavedRecipeFromJson(Map<String, dynamic> json) => SavedRecipe(
-  id: json['id'] as String,
-  title: json['title'] as String,
-  description: json['description'] as String?,
-  cuisine: json['cuisine'] as String?,
-  difficulty: json['difficulty'] as String?,
-  prepTimeMin: (json['prep_time_min'] as num?)?.toInt(),
-  cookTimeMin: (json['cook_time_min'] as num?)?.toInt(),
-  servings: (json['servings'] as num?)?.toInt(),
-  imageUrl: json['image_url'] as String?,
-  ingredients:
-      (json['ingredients'] as List<dynamic>?)
-          ?.map((e) => RecipeIngredient.fromJson(e as Map<String, dynamic>))
-          .toList() ??
-      [],
-  steps:
-      (json['steps'] as List<dynamic>?)
-          ?.map((e) => RecipeStep.fromJson(e as Map<String, dynamic>))
-          .toList() ??
-      [],
-  tags:
-      (json['tags'] as List<dynamic>?)?.map((e) => e as String).toList() ?? [],
-  nutrition: json['nutrition_per_serving'] == null
-      ? null
-      : NutritionInfo.fromJson(
-          json['nutrition_per_serving'] as Map<String, dynamic>,
-        ),
-  source: json['source'] as String,
-  savedAt: DateTime.parse(json['saved_at'] as String),
-);
-
-Map<String, dynamic> _$SavedRecipeToJson(SavedRecipe instance) =>
-    <String, dynamic>{
-      'id': instance.id,
-      'title': instance.title,
-      'description': instance.description,
-      'cuisine': instance.cuisine,
-      'difficulty': instance.difficulty,
-      'prep_time_min': instance.prepTimeMin,
-      'cook_time_min': instance.cookTimeMin,
-      'servings': instance.servings,
-      'image_url': instance.imageUrl,
-      'ingredients': instance.ingredients.map((e) => e.toJson()).toList(),
-      'steps': instance.steps.map((e) => e.toJson()).toList(),
-      'tags': instance.tags,
-      'nutrition_per_serving': instance.nutrition?.toJson(),
-      'source': instance.source,
-      'saved_at': instance.savedAt.toIso8601String(),
-    };
+// This file is intentionally empty.
+// saved_recipe.dart now uses a manually written fromJson/toJson.