P112 aux response queue

P112 put the P111 load response behind a one-entry registered queue. The queue is live: 3,677,395 enqueues, 3,677,395 dequeues, zero full drops, zero aux errors, and zero aux cancels.

The shell smoke reached P112-FILE-OK, but the timing got worse:

P111 shell window: 64,766,712 cycles
P112 shell window: 71,950,542 cycles
delta:             +7,183,830 cycles

This is a mechanism PASS and speedup FAIL. P113 should be a policy rung, not another raw mechanism rung.