Add NFS self-heal automation for immich/calibre/ocis, backed up in git

Stale NFS handles inside containers (ESTALE/errno -116) can persist even
after the host-side mount looks healthy, requiring a manual remount +
container restart. Adds systemd mount-ready hooks (BindsTo) to restart
immich_server/calibre/ocis when their NFS mount unit restarts, plus a
5-minute health-check timer that does a real nested read and force-remounts
on staleness. Host files backed up under system-config/nfs-self-heal/ so
they can be reinstalled after a host rebuild.

NAS-CONNECTION-STRATEGIES.md

@@ -115,6 +115,26 @@ Summary of how each service connects to the unRAID NAS (192.168.1.192 / 192.168.
 
 ---
 
+## Self-Healing (nas_family / nas_books / nas_owncloud)
+
+As of 2026-08-25, stale-handle recovery for immich, calibre, and oCIS is
+automated instead of requiring manual `systemctl restart` + `docker restart`:
+
+- `<container>-mount-ready.service` (`immich-mount-ready`, `calibre-mount-ready`,
+  `ocis-mount-ready`) — `BindsTo=mnt-nas_*.mount`, restarts the container
+  whenever its mount unit restarts.
+- `nfs-mount-heal.timer` (every 5 min) → `nfs-mount-heal.sh` — does a nested
+  file read (not just `ls` the mount root, which can succeed even when nested
+  handles are stale) against each of the three mounts. On failure it force-
+  remounts the mount unit, which cascades into the container restart above,
+  then sends a Telegram alert.
+
+Host files backed up at `system-config/nfs-self-heal/` in this repo (see its
+README for the reinstall procedure — these are systemd units, not
+docker-compose, so they don't redeploy via Portainer).
+
+---
+
 ## Recommended Migration (future)
 
 Plex, qBittorrent, Immich, and Audiobookshelf all use the fragile Docker NFS named volume pattern. The safer pattern is systemd permanent mount + Docker bind mount (as used by calibre-import and oCIS). This would involve: