feat(media): share one metadata set between Jellyfin and Plex over an SSD overlay

Both media servers read a Kodi-format sidecar (movie.nfo / tvshow.nfo /
episode.nfo) only when it sits next to the media file, and the library lives on
the RAID6 array, deliberately mounted read-only for every container and slow to
seek for a thousand tiny XML reads. So neither server binds the array any more:
both bind /mnt/media, an OverlayFS merge of the array (lowerdir, never written)
with /var/lib/media-meta on the NVMe (upperdir, where every write lands).

Jellyfin binds the view rw at /data and is the fleet's only metadata writer;
Plex binds it ro at /mnt/entropy, the container path its own database already
recorded, so only the host side of that bind moved and its library paths keep
resolving.

scripts/media-view.sh plans, installs, verifies, reports and reaps the view. It
refuses to mount over an unmounted array, refuses an upper layer on rotational
storage, and refuses a non-root install. deploy-remote.sh raises the view before
it restarts either media server, both units carry
ConditionPathIsMountPoint=/mnt/media so a missing view skips the start instead of
letting a scan clear the library database, and the planner routes the installer
and dankserver/host/** to the jellyfin+plex pair.

tests/media_overlay.bats (11 seams) pins the resolved shape, both refusals, the
two binds and their guard, the deployer's ordering, the planner mapping, and the
reap behaviour against a fixture (ghosts listed, then moved to the SSD trash --
files that exist only above are sidecars, not ghosts, so only directories are
candidates).

scripts/deploy-remote.sh

@@ -1202,7 +1202,21 @@ deploy_romm_stack() {
     systemctl --user restart "$service.service"
 }
 
+ensure_media_view() {
+    # Both media servers read their library through the SSD-backed overlay view
+    # (scripts/media-view.sh, dankserver/host/systemd/mnt-media.mount): the array
+    # below stays read-only and every sidecar Jellyfin writes lands on the NVMe.
+    # Raise it BEFORE either container starts — a start against a bare /mnt/media
+    # directory would let a scan clear the library database. The units also carry
+    # ConditionPathIsMountPoint, so a missing view skips the start rather than
+    # damaging anything. A relayout must be followed by `media-view.sh reap`
+    # (see the Media Relayout page), which this is not.
+    run_privileged bash scripts/media-view.sh install
+    bash scripts/media-view.sh verify
+}
+
 deploy_jellyfin() {
+    ensure_media_view
     cp "dankserver/jellyfin/quadlet/jellyfin.container" "$quadlet_unit_dir/"
     systemctl --user daemon-reload
     if ! systemctl --user is-active -q jellyfin.service; then
@@ -1290,6 +1304,7 @@ deploy_copyparty() {
 }
 
 deploy_plex() {
+    ensure_media_view
     cp "dankserver/plex/quadlet/plex.container" "$quadlet_unit_dir/"
     systemctl --user daemon-reload
     if ! systemctl --user is-active -q plex.service; then