compose: pull image for deploy instead of building

Dockhand pulls the CI-built image, so drop `build: .` (no build context
on the deploy host) and add pull_policy: always.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -15,8 +15,10 @@ services:
     restart: unless-stopped
 
   app:
-    build: .
+    # Pulled from the Forgejo registry (built by CI). To build locally instead:
+    #   docker build -t git.plexultra.com/dlawler489/printhive:latest .
     image: git.plexultra.com/dlawler489/printhive:latest
+    pull_policy: always
     depends_on:
       db:
         condition: service_healthy