Wire agent builder platform secret

deploy/20-deployment.yaml

@@ -36,6 +36,9 @@ spec:
               value: "1200"
             - name: DEPLOY_WAIT_TIMEOUT_S
               value: "900"
+            - name: A2A_PLATFORM_SECRET
+              valueFrom:
+                secretKeyRef: {name: platform-secrets, key: platform_secret}
             - name: A2A_LITELLM_URL
               value: http://litellm.llm.svc.cluster.local:4000
             - name: A2A_LITELLM_KEY