Providers that emit a fresh check run id per phase (e.g. Cloudflare Pages)
no longer post a new message for each status change; same name + commit
SHA now edits the existing message. Falls back to the run id when name or
head_sha is absent. Docs updated in sync.
formatCheckRun now sets a stable updateKey (check_run:{repo}:{id}) so queued → in_progress → completed phases update the original message via KV msg:* tracking instead of posting new ones. Adds tests and syncs README/docs.