sunken-ship: navidrome Scanner.PurgeMissing = missing

Stops `missing=1` rows accumulating in media_file. After Phase 7
dedupe, Navidrome's watcher minted ~4k track IDs for files briefly
present in /home/danny/music/.mulbo-quarantine; after rm -rf'ing
the quarantine, those rows stayed flagged-missing forever — and
Substreamer's cached queue then hit 500s on every play attempt
("Internal Server Error: open /srv/music/.mulbo-quarantine/...: no
such file or directory").

Cleaned the 4135 quarantine rows manually via SQL; this config
prevents recurrence. Trade-off: missing rows used to preserve
play-history across "file disappeared, came back" cycles. We prefer
client-cache hygiene.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

nixos/hosts/sunken-ship.nix

@@ -110,6 +110,12 @@
       Address = "0.0.0.0";
       Port = 4533;
       MusicFolder = "/srv/music";
+      # Auto-delete `missing=1` rows during scan so transient files
+      # (e.g. mulbo dedupe quarantine ones) don't accumulate as stale
+      # track IDs that Substreamer caches and then 500s on. Without
+      # this, Navidrome keeps missing rows forever (default behaviour
+      # preserves play history; we trade that for client-cache hygiene).
+      Scanner.PurgeMissing = "missing";
     };
   };