Closes#5697
- Extract buildUpdatedBotOptions (pure) and applyBotOptionUpdatesInOrder
(async orchestration) as top-level @visibleForTesting functions
- Handle bot DM independently of _targetBotChats filter — the DM may
lack a botOptions state event or have a stale activityPlan, but it's
the most important room to keep current
- Update remaining rooms sequentially (not Future.wait) to avoid rate-limiting
- DM errors propagate; other room errors are logged and isolated
- Add 17 unit tests covering both extracted functions
- Add profile.instructions.md design doc for profile settings architecture
