Resolve six review findings on the unified-send change:
- quiet (wakeup:false) queued items no longer un-park the driver; the
inbox distinguishes hasWakingQueued (drives the loop, idle/quiescence)
from hasQueued (anything to dequeue), so a lone quiet item parks at idle
and rides the next waking send. whenIdle/cancel settle off the waking
signal, so cancelling a parked quiet item no longer hangs whenIdle.
- SendOptions.meta on queued/steering sends now reaches the durable
user/message and steering/message (was dropped except on injection).
- a terminal agent/turn-stop that drops pending steering emits
agent/inbox/discard so the enqueue-dequeue-or-discard ledger balances.
- the loop-authored continuation reason is snapshotted and frozen like a
public send.
- gen-cordis-api collects exported classes (body-stripped) so the now-
abstract-class Agent and its transitive shapes reappear in the API
catalog.
Adds regression tests for each and re-records the affected snapshot.