Belt-and-braces against transient registry-1.docker.io blips (rate
limits, brief 5xx, CDN flap). Replaces docker/build-push-action@v7 with
a shell: bash step that runs docker buildx build --push in a for-loop
with backoff (15s, 30s).
Does NOT mask deterministic failures: a true regression (e.g. the
cache-export 400 we hit 2026-05-23..28) fails all 3 attempts
identically and the job still fails by design. Orthogonal layer to
both cache-export disablement and the ci-release-watcher skill's
transient-rerun heuristic.
No image-side change.
pi
2d397663d5