refactor: migrate to ES modules

package.json type=module, tsconfig module/moduleResolution=NodeNext,
target es2022, explicit .js on all relative imports. Center: jsonwebtoken
& bcryptjs switched to default imports (ESM/CJS interop). Verified:
builds, boots, full auth + plugin round-trip work under ESM.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/data-source.ts

@@ -1,6 +1,6 @@
 import 'reflect-metadata';
 import { DataSource, DataSourceOptions } from 'typeorm';
-import { buildTypeOrmConfig } from './database.config';
+import { buildTypeOrmConfig } from './database.config.js';
 
 const cfg = buildTypeOrmConfig();