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>

scripts/nfs-mirror.timer

@@ -1,16 +0,0 @@
-[Unit]
-Description=Daily local NFS mirror to /mnt/backup
-
-[Timer]
-# Daily 02:00 — runs 3h before daily-backup (05:00) so the .changed-files
-# manifest is populated and offsite-sync (06:00) ships both legs' deltas.
-# Switched from weekly Mon 04:00 → daily 2026-05-26: steady-state delta is
-# 10-20 min of mostly-metadata rsync, so the IO cost is negligible and it
-# cuts non-CronJob app-data RPO from 7d to ~24h (matters for nextcloud
-# shared files, audiobookshelf library, mailserver Maildir, etc.).
-OnCalendar=*-*-* 02:00:00
-Persistent=true
-RandomizedDelaySec=15min
-
-[Install]
-WantedBy=timers.target