Follow-up cleanup on the human-input timeout work.
- Drop the `unresolved_interviews` counter from `InterviewBlockState`. It
duplicated `blocked_stages`, which is non-empty exactly when the run is
blocked.
- Publish block state before emitting `run.blocked` / `run.unblocked` in
both directions, so a listener reading `subscribe()` from an event
callback never sees state that disagrees with the event. The watchdog
still gets a full fresh deadline because it restarts on the unblock
transition.
- Stop panicking in `InterviewBlockState::resolve`. It runs from `Drop`,
where a panic during unwind aborts the process.
- Replace the emitter's `activity_revision` watch channel with a
monotonic timestamp. `record_activity` runs on every agent stream
delta, and the channel woke the watchdog task and re-armed its timer
per event. The watchdog now samples `last_activity()` when its deadline
fires and re-arms only if the run was active, so the hot path is one
clock read and one relaxed store.
- Remove the now-unused `last_event_at()` and `epoch_millis()`.
- Collapse the duplicated blocked/unblocked `select!` arms in
`monitor_for_stall` and `timeout_excluding_interview_wait` into one
loop each, using a branch precondition to park the timer while blocked.
- Handle a dropped block-state sender in
`timeout_excluding_interview_wait` by falling back to a plain deadline
instead of panicking, which also removes a potential busy loop.
- Only compute `stage_id` when the node actually has a timeout.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
