Adds the fn pr noun — create/show/list/respond/approve/retry/merge/close/
automerge — routing to the same store/engine/release paths as the U7
dashboard routes (surface-parity pinned by a consistency test). Retires
fn task pr-create (dispatch removed; deprecated re-export kept for
importers). Changeset: @runfusion/fusion minor. 22 command tests.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>