GET /tasks/:id/activity returns a time-sorted ActivityItem[] assembled from existing data (task created, handoffs by taskId, memory by relatedTasks, current status). memory add + task done gain optional tokens/duration/by metadata surfaced in the timeline. Board cards expand inline to show the timeline. Index gains taskId + relatedTasks columns with migrations. 74 -> 97 tests.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
