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.

serverAppConfigs-docs/Dankserver/Jellyfin.md

@@ -26,7 +26,7 @@ public vhost `jelly.franksdank.cloud` behind the [[Anubis]] guard chain →
 | Image | `ghcr.io/jellyfin/jellyfin:latest` |
 | Network | `dankserver_appnet`; publishes 8096/tcp, 8920/tcp, 7359/udp, 1900/udp |
 | Data roots | `/home/dank/Containers/jellyfin/config:/config`, `/home/dank/Containers/jellyfin/cache:/cache` |
-| Media | `Volume=/mnt/media:/data` — the [[Media Metadata View]] overlay, **writable**; sidecars land on the NVMe, the [[Entropy Volume]] array underneath stays read-only and untouched |
+| Media | `Volume=/var/lib/media-meta/view:/data` — the [[Media Metadata View]] overlay, **writable**; sidecars land on the NVMe, the [[Entropy Volume]] array underneath stays read-only and untouched |
 | GPU | none — no `AddDevice`; CPU decode only (jellyfin-ffmpeg path) |
 | Env quirks | `DOTNET_SYSTEM_IO_DISABLEFILELOCKING=true`, `LD_PRELOAD=libjemalloc.so.2`, `MALLOC_TRIM_THRESHOLD_=131072` kept verbatim from the compose-era container (zero-drift cutover) |
 | Health | `curl -f http://localhost:8096/health` every 30 s |
@@ -36,7 +36,7 @@ public vhost `jelly.franksdank.cloud` behind the [[Anubis]] guard chain →
 ```
 /home/dank/Containers/jellyfin/config   -> /config   (JELLYFIN_DATA_DIR)
 /home/dank/Containers/jellyfin/cache    -> /cache    (JELLYFIN_CACHE_DIR, XDG_CACHE_HOME)
-/mnt/media                             -> /data     (the SSD-backed overlay view)
+/var/lib/media-meta/view                -> /data     (the SSD-backed overlay view)
 ```
 
 Library folders point at `/data` paths, which are the view's paths: stable