Add docker-compose and fix CI network creation

.gitea/workflows/deploy.yml

@@ -16,6 +16,9 @@ jobs:
       - name: Extract version tag
         run: echo "VERSION_TAG=${GITHUB_REF_NAME}" >> $GITHUB_ENV
 
+      - name: Create shared network if missing
+        run: docker network create poster-picker || true
+
       - name: Build Docker image
         run: docker compose build