chore(hub): update instance health state

Author: github-actions[bot]

.github/hub-health.json

@@ -1 +1,6 @@
-{}
+{
+  "xiaoten": {
+    "url": "https://echo.xiaoten.com",
+    "unhealthy_since": "2026-08-31T02:43:37.310Z"
+  }
+}