chore: remove obsolete environment variables from arty.yml

Removed duplicate STASH_* and JELLY_* variables that have been replaced by MEDIA_* variables after consolidation into the media stack.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

arty.yml

@@ -78,18 +78,7 @@ envs:
     UTIL_JOPLIN_DB_NAME: joplin
     # PairDrop
     UTIL_DROP_TRAEFIK_HOST: drop.pivoine.art
-    # Filestash
-    STASH_TRAEFIK_ENABLED: true
-    STASH_COMPOSE_PROJECT_NAME: stash
-    STASH_IMAGE: machines/filestash:latest
-    STASH_TRAEFIK_HOST: stash.pivoine.art
-    STASH_PORT: 8334
-    STASH_CANARY: true
-    # Jellyfin
-    JELLY_TRAEFIK_ENABLED: true
-    JELLY_COMPOSE_PROJECT_NAME: jelly
-    JELLY_TRAEFIK_HOST: jelly.pivoine.art
-    # Media Stack (Jellyfin, Filestash, Koel)
+    # Media Stack (Jellyfin, Filestash)
     MEDIA_TRAEFIK_ENABLED: true
     MEDIA_COMPOSE_PROJECT_NAME: media
     MEDIA_JELLYFIN_IMAGE: jellyfin/jellyfin:latest