[WIP] Sidebar v2 beta: flat adaptive-density thread list with settled lifecycle - #3960

Bugbot Analysis Progress (15m 15s elapsed)

✅ Gathered PR context (6s)
✅ Completed bug detection (15m 8s)
✅ Posted analysis results (1s)

Final Result: Bugbot completed review - no issues found. 8 previously reported issues remain unresolved.

Request ID: serverGenReqId_40f63de3-4b3d-47cd-bc4f-651138bab051