stacks: use each app's real default port instead of arbitrary fleet ports

Replaced 29 host-port values across 27 stacks with the app's own
well-known default (read directly from each compose file's own
container-side port mapping) instead of the arbitrary port numbers
this fleet actually assigns to avoid collisions across ~44 services
on one host. More recognizable to a reader, and removes the last
fleet-specific detail these files carried.

Also removes a stale adminer service from n8n's stack entirely
(compose service + .env var) - it's no longer actually deployed.

stacks/media/beets/.env

@@ -1,5 +1,5 @@
 # Exposed HTTP port
-HTTP_PORT=8164
+HTTP_PORT=8337
 
 # System time zone
 TZ=Etc/UTC