- Add detectKeyword() and handleConsentKeyword() in consent.ts
- Wire keyword detection into handleMessageReceived() in inbound.ts
- Add 24-unit test suite for consent.ts covering all keywords,
case insensitivity, whitespace tolerance, idempotency, and
help keyword state preservation
Fixes from QA review:
- Use getDb() instead of non-existent db export; import Db type
- Destructure clientId from findOrCreateConversation result
- Rename staffId → sentByStaffId in sendMessage call
- Remove messagingHelpReply query (column not yet in schema)
Co-Authored-By: Paperclip <noreply@paperclip.ing>
