fix(CQ-API-4): Remove Redis event listeners in onModuleDestroy

Add removeAllListeners() call before quit() to prevent memory leaks
from lingering event listeners on the Redis client.

Also update test mock to include removeAllListeners method.

Refs #339

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/valkey/valkey.service.spec.ts

@@ -24,6 +24,10 @@ vi.mock("ioredis", () => {
       return this;
     }
 
+    removeAllListeners() {
+      return this;
+    }
+
     // String operations
     async setex(key: string, ttl: number, value: string) {
       store.set(key, value);

apps/api/src/valkey/valkey.service.ts

@@ -63,8 +63,10 @@ export class ValkeyService implements OnModuleInit, OnModuleDestroy {
     }
   }
 
-  async onModuleDestroy() {
+  async onModuleDestroy(): Promise<void> {
     this.logger.log("Disconnecting from Valkey");
+    // Remove all event listeners to prevent memory leaks
+    this.client.removeAllListeners();
     await this.client.quit();
   }