Reliability pass over every workflow:
- timeout-minutes on all 21 jobs that lacked one (a hung job previously
burned the 6-hour default runner budget)
- ./.github/actions/retry wrapped around every network-fetching install
that lacked it: pip installs (deploy-site, skills-index), npm ci
(deploy-site website, upload_to_pypi web + ui-tui), uv sync (docker
test deps). Deterministic build steps (npm run build) deliberately
NOT retried — split into separate steps so a real build failure fails
fast instead of retrying 3x.