fix: Docker 构建加 --no-cache 禁用缓存（修复 Celery 镜像代码过期）

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/deploy.yaml

@@ -33,6 +33,7 @@ jobs:
           set -o pipefail
           docker buildx build \
             --push \
+            --no-cache \
             --provenance=false \
             --tag ${{ secrets.SWR_SERVER }}/${{ secrets.SWR_ORG }}/video-backend:latest \
             ./backend 2>&1 | tee /tmp/build.log