fix(scheduler): abort queued wake inject on cancel; purge goal-check on terminal cancel

[cursor]

Bug and impact

1. Queued agent_wake inject permanently lost on session cancel

• Impact: Scheduled / goal wakes silently stopped after terminal cancel if the inject was still queued (not yet dispatched). poll_due_wakes never retried because the wake stayed staged=True.
• Root cause: _dispatch_loop skipped cancelled queued requests without calling _finalize_agent_wake_delivery(confirmed=False). Only _run_and_route had the abort path.
• Trigger: Due wake → inject_turn enqueues + _mark_staged → user cancels before dispatch dequeues → skip at dispatch with no abort → wake stuck staged forever.

2. Terminal cancel flushed staged goal-check wakes

• Impact: User Ctrl+C / dashboard cancel during a running turn could immediately re-inject a staged goal-check wake in finally, restarting auto-continue right after abort.
• Root cause: cancel_session_tasks did not purge _PENDING_BY_SESSION goal-check entries; flush_pending_wakes_for_session still delivered them when inflight hit zero.
• Trigger: Long turn in flight → goal-check wake staged (inflight>0) → terminal cancel → finally flush delivers wake inject.

Fix

• Call _finalize_agent_wake_delivery(request, confirmed=False) when dispatch skips a cancelled queued request.
• Call cancel_pending_wakes(session_id, label="goal-check") at the start of cancel_session_tasks.

Validation

• tests/test_kernel_runtime.py::test_cancel_dispatch_skip_aborts_agent_wake_delivery
• tests/test_kernel_runtime.py::test_terminal_cancel_does_not_flush_staged_goal_check
• Existing test_cancel_skip_aborts_agent_wake_delivery still passes