Gitea drops an invalid workflow file with one log line and fires no run, so
the GitHub PR showed nothing and lanes waited for CI that never came
(windytalk #100). The bridge now reads each workflow file at the commit it
reports on and posts windy-git/<wf>/workflow = error with the reason.
Verified: 0 false positives on all 23 bridged repos' main; catches
windytalk #100's broken commits (invalid YAML at line 12), fix commit clean.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>