feat: implement AdminGuard and QueryGuard for enhanced access control; refactor API and query handling; add deleteQuery method in QueryHandlerService; update QueryResponse type for improved response handling

src/api/guards/admin.guard.ts

@@ -0,0 +1,27 @@
+import {
+  CanActivate,
+  ExecutionContext,
+  Inject,
+  Injectable,
+  UnauthorizedException,
+} from "@nestjs/common";
+import { ApiService } from "../api.service";
+
+@Injectable()
+export class AdminGuard implements CanActivate {
+  constructor(
+    @Inject(ApiService)
+    private readonly apiService: ApiService
+  ) {}
+
+  async canActivate(context: ExecutionContext): Promise<boolean> {
+    const request = context.switchToHttp().getRequest();
+    const apiToken = request.apiToken;
+
+    if (!apiToken || !apiToken.isAdmin) {
+      throw new UnauthorizedException("Admin privileges are required");
+    }
+
+    return true;
+  }
+}