feat(db): enable schema migration using sql.js and export to data/recipes.db

TODO.md

@@ -10,7 +10,7 @@
 ### Backend Setup
 - [x] Initialize Node.js backend: Create src/backend/, package.json with express, better-sqlite3, zod, vitest. Create src/backend/index.ts with "Hello World" server on port 3000. Verify: npm install && npm run dev (server starts). Commit as "feat(backend): initialize Node.js project with Express"
 - [x] Set up TypeScript: Create tsconfig.json (strict mode, ES2022, Node16 module resolution). Add build script to package.json. Verify: npm run build succeeds. Commit.
-- [ ] Create SQLite schema: Create src/backend/db/schema.sql with recipes, tags, recipe_tags tables per ARCHITECTURE.md. Create src/backend/db/migrate.ts to apply schema. Verify: npm run migrate creates data/recipes.db. Commit.
+- [x] Create SQLite schema: Create src/backend/db/schema.sql with recipes, tags, recipe_tags tables per ARCHITECTURE.md. Create src/backend/db/migrate.ts to apply schema using sql.js (see ADR-001). Verify: npm run migrate creates data/recipes.db. Commit.
 - [ ] Implement recipe CRUD API endpoints
 - [ ] Add Zod validation schemas
 - [ ] Write API integration tests

src/backend/db/migrate.ts

@@ -0,0 +1,36 @@
+import initSqlJs from 'sql.js';
+import fs from 'fs';
+import path from 'path';
+
+const DATA_DIR = path.resolve(process.cwd(), 'data');
+const DB_PATH = path.join(DATA_DIR, 'recipes.db');
+const SCHEMA_PATH = path.resolve(process.cwd(), 'src/backend/db/schema.sql');
+
+async function ensureDataDir() {
+  if (!fs.existsSync(DATA_DIR)) {
+    fs.mkdirSync(DATA_DIR, { recursive: true });
+    console.log(`Created data directory at ${DATA_DIR}`);
+  }
+}
+
+async function applyMigrations() {
+  await ensureDataDir();
+  
+  const schema = fs.readFileSync(SCHEMA_PATH, 'utf8');
+  const SQL = await initSqlJs();
+  const db = new SQL.Database();
+  
+  // Run all SQL statements
+  db.exec(schema);
+
+  // Export and save to file
+  const data = db.export();
+  fs.writeFileSync(DB_PATH, Buffer.from(data));
+  console.log(`Database migrated: ${DB_PATH}`);
+}
+
+if (import.meta.url === `file://${process.argv[1]}`) {
+  applyMigrations();
+}
+
+export { applyMigrations };

src/backend/db/schema.sql

@@ -0,0 +1,38 @@
+-- Create recipes table
+CREATE TABLE recipes (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  title TEXT NOT NULL,
+  description TEXT,
+  ingredients TEXT NOT NULL, -- JSON array
+  instructions TEXT NOT NULL, -- JSON array of steps
+  source_url TEXT,
+  notes TEXT,
+  servings INTEGER,
+  prep_time_minutes INTEGER,
+  cook_time_minutes INTEGER,
+  created_at INTEGER NOT NULL,
+  updated_at INTEGER NOT NULL,
+  last_cooked_at INTEGER
+);
+
+-- Create tags table
+CREATE TABLE tags (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  name TEXT UNIQUE NOT NULL,
+  color TEXT -- Hex color for UI
+);
+
+-- Create recipe_tags join table
+CREATE TABLE recipe_tags (
+  recipe_id INTEGER NOT NULL,
+  tag_id INTEGER NOT NULL,
+  PRIMARY KEY (recipe_id, tag_id),
+  FOREIGN KEY (recipe_id) REFERENCES recipes(id) ON DELETE CASCADE,
+  FOREIGN KEY (tag_id) REFERENCES tags(id) ON DELETE CASCADE
+);
+
+-- Indexes for efficiency
+CREATE INDEX idx_recipes_title ON recipes(title);
+CREATE INDEX idx_recipes_created_at ON recipes(created_at DESC);
+CREATE INDEX idx_recipe_tags_recipe ON recipe_tags(recipe_id);
+CREATE INDEX idx_recipe_tags_tag ON recipe_tags(tag_id);