refactor(media): mount the view inside /var/lib/media-meta instead of under /mnt

The merged door was /mnt/media, which read like a third volume and split the host
state across two trees. It is now /var/lib/media-meta/view, so the array layer,
the SSD upper layer, the kernel workdir, the reap trash and the merged tree are
one directory — and the mount table gains no new /mnt entry beside the array.

systemd names a mount unit after its ESCAPED path, so the repo copy keeps the
readable name media-meta-view.mount while `install` writes the host file as
var-lib-media\x2dmeta-view.mount; `plan` prints both and the page records them, so
nobody hunts for a unit that "does not exist". install also creates the mount
point itself, because systemd will not.

The seam now additionally pins that the unit's Where= is exactly the path both
containers bind — guard and bind cannot drift apart. The Quadlet Lifecycle
phantom-path example is corrected too: it named an invented /mnt/media/*, while
the real phantom is the legacy /opt/jellyfin/* that dankserver/compose.yaml still
carries for a service whose roots moved to /home/dank/Containers/jellyfin.

dankserver/jellyfin/quadlet/jellyfin.container

@@ -4,9 +4,9 @@
 # Unit name: jellyfin.service (podman 5.x drops the container- prefix)
 #
 # Data roots migrated from /opt/jellyfin to /home/dank/Containers/jellyfin at
-# cutover. The library is seen through /mnt/media, the SSD-backed overlay view
-# (scripts/media-view.sh): the array stays read-only and untouched, while the
-# sidecars this server writes land on the NVMe. Every
+# cutover. The library is seen through /var/lib/media-meta/view, the SSD-backed
+# overlay view (scripts/media-view.sh): the array stays read-only and untouched,
+# while the sidecars this server writes land on the NVMe. Every
 # creation-time environment variable of the compose-era container is kept as
 # an Environment= line (zero drift); none of them are secrets, so this unit
 # needs no EnvironmentFile.
@@ -44,10 +44,10 @@ Volume=/home/dank/Containers/jellyfin/config:/config
 Volume=/home/dank/Containers/jellyfin/cache:/cache
 # The view, writable: Jellyfin is the metadata writer (movie.nfo / tvshow.nfo /
 # episode.nfo + artwork) and those bytes belong on the SSD. The condition is the
-# fail-closed guard — starting against a plain /mnt/media directory would let a
-# scan conclude the library is empty.
-Volume=/mnt/media:/data
-UnitConfigItem=ConditionPathIsMountPoint=/mnt/media
+# fail-closed guard — starting against a plain, unmounted view directory would let
+# a scan conclude the library is empty.
+Volume=/var/lib/media-meta/view:/data
+UnitConfigItem=ConditionPathIsMountPoint=/var/lib/media-meta/view
 AddDevice=/dev/dri
 GroupAdd=keep-groups
 HealthCmd=curl -f http://localhost:8096/health