fix gateway loopback validation chains

packages/contracts/src/index.ts

@@ -560,7 +560,7 @@ export interface PlatformModel {
   platformName?: string;
   modelName: string;
   modelAlias?: string;
-  modelType: 'chat' | 'image' | 'video' | 'audio' | 'embedding' | string;
+  modelType: string[];
   displayName: string;
   capabilityOverride?: Record<string, unknown>;
   capabilities?: Record<string, unknown>;
@@ -625,6 +625,8 @@ export interface GatewayTask {
   responseDurationMs?: number;
   finishedAt?: string;
   error?: string;
+  errorCode?: string;
+  errorMessage?: string;
   createdAt: string;
   updatedAt: string;
 }