fix: switch backend to CommonJS, generate Drizzle migrations, add migrate script

- Remove "type": "module" and switch tsconfig to CommonJS/Node resolution
  to fix drizzle-kit ESM/CJS incompatibility
- Strip .js extensions from all backend TypeScript imports
- Fix gamification resolver: combine two .where() calls using and()
- Fix index.ts: wrap top-level awaits in async main(), fix Fastify+yoga
  request handling via handleNodeRequestAndResponse
- Generate initial Drizzle SQL migration (0000_pale_hellion.sql) for all
  15 tables
- Add src/scripts/migrate.ts: programmatic Drizzle migrator for production
- Copy migrations folder into Docker image (Dockerfile.backend)
- Add schema:migrate npm script

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

packages/backend/src/scripts/migrate.ts

@@ -0,0 +1,23 @@
+import { Pool } from "pg";
+import { drizzle } from "drizzle-orm/node-postgres";
+import { migrate } from "drizzle-orm/node-postgres/migrator";
+import path from "path";
+
+const pool = new Pool({
+  connectionString: process.env.DATABASE_URL || "postgresql://sexy:sexy@localhost:5432/sexy",
+});
+
+const db = drizzle(pool);
+
+async function main() {
+  console.log("Running schema migrations...");
+  const migrationsFolder = path.join(__dirname, "../../migrations");
+  await migrate(db, { migrationsFolder });
+  console.log("Schema migrations complete.");
+  await pool.end();
+}
+
+main().catch((err) => {
+  console.error("Migration failed:", err);
+  process.exit(1);
+});