Source .env before docker stack deploy in CI

docker stack deploy does not read .env files automatically
(unlike docker compose), so ${VAR} substitutions resolve to
empty strings. Source .env to export vars before deploying.

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

.gitea/workflows/ci.yml

@@ -55,6 +55,7 @@ jobs:
         run: |
           ssh "root@$DEPLOY_HOST" "
             cd /root/art-dag/celery
+            set -a && source .env && set +a
             docker stack deploy -c docker-compose.yml celery
             echo 'Waiting for services to update...'
             sleep 10