Reset & Retry discarded the branch and queued an autonomous run even while the
user had an interactive ConPTY pane open on the task, and finalizing a plan
queued every child unconditionally (the hub has no notion of a UI-hosted
session) — both bypassed the HasInteractiveSession gate added for
CanSendToQueue. CanResetAndRetry now checks it too, with a subscription on the
bound task so the command re-evaluates when the flag flips without Task
itself changing; SendToQueueAsync now blocks queuing the whole plan and
surfaces the affected child titles when any child has an open session.
