add tests for Task 10 worker extensions (posts, deletes, accounts, quotes)
16 new tests covering:
- post create by tracked author → snapshot buffered with zero counts
- post create by untracked author → no snapshot
- quote by untracked author embedding tracked author → quote engagement
- quote by tracked author embedding tracked author → snapshot AND quote
- quote embedding untracked author → no quote engagement
- post delete for tracked author → tombstonePost called
- post delete for untracked author → dropped
- account deleted → markUserDeleted + tombstoneUserSnapshots + DID removed
- account takendown → same as deleted
- account deactivated/suspended → dropped
- identity event for tracked user → handle updated
- identity event for untracked user → dropped
- DID removed from tracked set after account deletion
Plus tombstoneUserSnapshots integration test in clickhouse_store.spec.ts.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>