A deploy request whose rev hive-c0re refuses (fetch failed, or the rev
does not descend from applied/main) no longer tries to comment on the PR
that merged it. Off the forge host that attempt always failed with "forge
core token absent". The refusal now logs at ERROR, message unchanged, and
the new `hh-config-rev-refused` Grafana rule fires on it.
Deleted with the posting: actions::post_rev_deploy_failure_to_pr, the
whole forge/pr_comment.rs (config_repo, merged_pr_for_commit,
post_pr_comment), and ReaderToken::value, whose only caller was
merged_pr_for_commit.
Refs #4851
8c222f8910