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>

.env.example

@@ -3,8 +3,7 @@
 # Anything left out uses the default shown here.
 
 # ---- container ----
-# Image tag to build/run and the container's name.
-PLAYLINK_IMAGE=playlink:latest
+# The container's name. (The image is built from this repository.)
 PLAYLINK_CONTAINER_NAME=playlink
 # Version label shown in the UI footer.
 PLAYLINK_VERSION=dev

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}"