chore: Cache bust CI stale files

Add comments to force CI to fetch fresh files instead of using stale cached versions

Author: jotel-dev

backend/src/services/sse.service.ts

@@ -234,4 +234,5 @@ export class SSEService {
   }
 }
 
+// Cache bust: CI fix
 export const sseService = new SSEService();

backend/src/workers/soroban-event-worker.ts

@@ -740,4 +740,5 @@ export class SorobanEventWorker {
   }
 }
 
+// Cache bust: CI fix
 export const sorobanEventWorker = new SorobanEventWorker();