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/host/systemd/media-meta-view.mount

@@ -1,4 +1,6 @@
-# /etc/systemd/system/mnt-media.mount
+# /etc/systemd/system/var-lib-media\x2dmeta-view.mount
+# (repo copy: dankserver/host/systemd/media-meta-view.mount — systemd names a
+# mount unit after its ESCAPED path, so the host file carries the \x2d spelling)
 #
 # Installed by `scripts/media-view.sh install` — the repo copy is the source of
 # truth (fleet law: never edit host state by hand).
@@ -6,7 +8,7 @@
 # An OverlayFS merge that shows the media library as one tree while splitting
 # where its bytes live: lowerdir is the RAID6 array (the source of truth, never
 # written), upperdir is a directory on the NVMe that receives every write. The
-# two media servers bind the result at /mnt/media, so Jellyfin's Kodi-format
+# two media servers bind the result at /var/lib/media-meta/view, so Jellyfin's
 # sidecars and artwork are SSD bytes — which is what makes them fast to browse
 # and what keeps Plex's NFO agent off the spinners — while the media itself stays
 # on the array untouched.
@@ -20,7 +22,7 @@ RequiresMountsFor=/mnt/entropy
 
 [Mount]
 What=overlay
-Where=/mnt/media
+Where=/var/lib/media-meta/view
 Type=overlay
 Options=lowerdir=/mnt/entropy,upperdir=/var/lib/media-meta/upper,workdir=/var/lib/media-meta/work