Number of priority ranks (0 most urgent); default one.
Private ReadonlycapacityRead at every admission, so a live-tunable cap applies to the next acquisition.
Wait for a place. Resolves with the release; rejects with the signal's
reason (or an AbortError) if signal aborts first, freeing the queue
place, and at once for an already-aborted signal.
Optionalsignal: AbortSignalRank to queue under (clamped to the gate's ranks).
Reject every queued waiter with reason and zero the counts (test isolation).
Read at every admission, so a live-tunable cap applies to the next acquisition.