A5-2: bridge.py now posts Gitea commit statuses on the recipe PR's head SHA:
- pending on build trigger (so testme-on-pr.sh sees the run immediately)
- success/failure on build finish (so testme-on-pr.sh returns VERDICT=GREEN/RED)
Added post_commit_status() using the existing _api() helper + GITEA_TOKEN.
Called from process_testme() (pending) and watch_and_reflect() (terminal state).
A5-1: added recipe-maintainers/custom-html-tiny to bridge POLL_REPOS in
bridge.nix so !testme on custom-html-tiny PRs is picked up by the bridge poller.
