feat: add database indexes, implement CORS configuration, and lazy-load frontend routes

paperless-backend/src/main.ts

@@ -7,7 +7,7 @@ async function bootstrap(): Promise<void> {
   const port = process.env.PORT ?? 3100;
 
   app.enableCors({
-    origin: '*', // Für lokale Entwicklung zulassen, oder spezifisch: 'http://localhost:8080'
+    origin: process.env.CORS_ORIGIN ?? (process.env.NODE_ENV === 'production' ? false : '*'),
     methods: 'GET,HEAD,PUT,PATCH,POST,DELETE,OPTIONS',
     credentials: true,
   });