--run <id> against a run that was itself PR-triggered has the identical
defect #4632 fixed for --pr: a workflow_dispatch run writes no commit
status, so it can't clear the red (pull_request) check on that PR's sha
no matter how the dispatched run turns out.
resolve_run already distinguishes this case -- it recognizes a run's
prettyref as a PR pseudo-ref (#<n>) via pr_number_from_run_ref, then
used to call branch_for_pr to keep going. It now bails with the same
pr_refusal_message --pr uses instead, before ever building a dispatch
request. branch_for_pr has no other caller (--pr refuses before
touching it too, since #4632), so it's removed rather than left dead.
Push (non-PR-triggered) and --branch are untouched.
Regenerated docs/tools/forge-cli.md from clap help; corrected
docs/tools/forge.md's claim that --run always works.