c0bca5c12d
registry.itsh.dev runs Zot, which only accepts OCI image indexes with SLSA provenance attestations. A plain 'docker build && docker push' produces a bare manifest and is rejected with 'manifest invalid' — the same gotcha documented in self-hosted/ente. The script mirrors that working pattern: buildx with --provenance mode=max, --platform linux/amd64, integrated --push. Auto-detects the default tag from cronjob.yaml so build-push and the manifest can't drift; override with TAG= when releasing a new version.