When a foreground message interrupts an autonomous turn, the notification
content has already been dispatched to subscribers. Canceling says "this
turn didn't happen" — but it did. Complete it instead, preserving the
lifecycle semantics and preventing notification loss.
- Change interrupt() to call completeAutonomousTurn instead of
cancelAutonomousTurn, with flushPendingToolCalls before completion
- Remove dead cancelAutonomousTurn method (no remaining callers)
- Fix autonomous wake tests B and C to handle notification/foreground
timing race: when task_notification arrives during a foreground turn,
there is no separate autonomous running edge afterwards