chore: store VHD build timestamp

aks-node-assistant[bot] · web-flow · commit b2ec076d0533 · 2026-03-04T22:45:38.000Z
diff --git a/vhdbuilder/vhd_build_timestamp.json b/vhdbuilder/vhd_build_timestamp.json
@@ -0,0 +1,3 @@
+{
+  "build_timestamp": "20260304T204100Z"
+}
