Fix database initialization: run migrations on server startup

Users on Windows were getting "no such table: users" errors because
migrations were never executed. The migrate.ts file existed but was
not imported by the server entry point.

server/src/index.ts

@@ -24,6 +24,7 @@ import playlistsRoutes from './routes/playlists.js';
 import contactRoutes from './routes/contact.js';
 import referenceTrackRoutes from './routes/referenceTrack.js';
 import { pool } from './db/pool.js';
+import './db/migrate.js';
 
 const app = express();