New services/consolidation.py module with maybe_consolidate() — the
debounced trigger gate. Two reasons:
- log_added: gated by DEFAULT_LOG_THRESHOLD (3) counted since the task's
consolidated_at timestamp.
- task_closed: bypasses the count gate; fires whenever status flips to
done/cancelled.
Both reasons gated by the auto_consolidate_tasks user setting (default
on). Per-task asyncio.Lock prevents two simultaneous passes for the same
task. consolidate_task is a stub here — full implementation in the next
commit.
