Gitea >= 1.27 does not propagate the caller's workflow_dispatch inputs
into a called workflow's github.event (same rework that changed
event_name), so a manual 'review PR #N' dispatch arrived with an empty
PR and died at the entrypoint's 'PR required' check. Accept pr_number as
an explicit workflow_call input and fold it into the PR env fallback
chain; caller stubs pass github.event.inputs.pr_number through.
Co-Authored-By: Claude Fable 5 <[email protected]>