fix(ci): add docker compose down before up to resolve container name conflict

The VPS has orphan containers from previous deployments that conflict with
new compose up. Running compose down --remove-orphans first cleans them up.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/workflows/deploy-docker.yml

@@ -140,5 +140,6 @@ jobs:
             echo "$GHCR_TOKEN" | docker login ghcr.io -u "$GHCR_USERNAME" --password-stdin
 
             docker compose pull
+            docker compose down --remove-orphans || true
             docker compose up -d --force-recreate --remove-orphans
             docker image prune -f