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/productivity/ghost/.env

@@ -1,4 +1,4 @@
-HTTP_PORT=10368
+HTTP_PORT=2368
 TZ=Etc/UTC
 
 GHOST_URL=https://blog.example.com
@@ -9,7 +9,7 @@ DB_HOST=ghost_db
 DB_NAME=ghostdb
 DB_USER=ghostuser
 
-UMAMI_PORT=3050
+UMAMI_PORT=3000
 UMAMI_DB_NAME=umami
 UMAMI_DB_USER=umami