Build the image instead of pulling it on deploy

Arcane pulls every service's image: reference before deploying, and
playlink isn't published to a registry. Drop the image name and set
pull_policy: build so the image is always built from the repository.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docker-compose.yml

@@ -7,7 +7,10 @@ services:
       context: .
       args:
         VERSION: ${PLAYLINK_VERSION:-dev}
-    image: ${PLAYLINK_IMAGE:-playlink:latest}
+    # No image: line on purpose. The image is always built from this
+    # repository, never pulled (it isn't published to a registry), so
+    # deploy tools like Arcane don't try to pull a name that doesn't exist.
+    pull_policy: build
     container_name: ${PLAYLINK_CONTAINER_NAME:-playlink}
     # Run as the user that owns your music (Unraid: nobody:users = 99:100).
     user: "${PUID:-99}:${PGID:-100}"