stem95su: scheduled Drive->site sync CronJob (every 10m)

CronJob stem95su-gdrive-sync (*/10) mounts the content PVC RW and
rclone-syncs the read-only Drive folder "claude" (stem claude/files) onto
it (rclone/rclone:1.74.3, scope=drive.readonly, empty-source guard +
--max-delete 25). ESO ExternalSecret stem95su-rclone <- Vault
secret/stem95su. Requires the GCP OAuth app published to Production or the
refresh token expires ~weekly.

Lands the gdrive-sync stack on master (it had landed on a feature branch
by accident on the shared devvm checkout).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.planning/config.json

@@ -1,12 +0,0 @@
-{
-  "mode": "yolo",
-  "depth": "comprehensive",
-  "parallelization": false,
-  "commit_docs": true,
-  "model_profile": "quality",
-  "workflow": {
-    "research": true,
-    "plan_check": true,
-    "verifier": true
-  }
-}