feat: increase ad retrieval limit in login response

apps/box-app-api/src/feature/auth/auth.service.ts

@@ -102,7 +102,7 @@ export class AuthService {
 
     // 5) startupAds (placeholder: you’ll wire channel-specific ads later)
     // For now return null to keep behaviour deterministic.
-    const startupAds = await this.adService.listAdsByType(1, 20);
+    const startupAds = await this.adService.listAdsByType(1, 500);
 
     return {
       uid,