Replace the file-editing onboarding workflow with a chat-native pairing flow:
- New pairing store (nanobot/pairing/store.py) persists approved senders
and pending codes in ~/.nanobot/pairing.json.
- DM messages from unknown senders receive a short pairing code instead of
silent denial. Group chats remain silently ignored.
- Existing allowFrom semantics are fully preserved; approved pairing users
are merged at runtime so no config migration is needed.
- nanobot pairing list/approve/deny/revoke CLI commands for bootstrap and
emergency management.
- /pairing slash commands intercepted in-channel so owners can approve
senders without leaving the chat.
- is_dm flag added to BaseChannel._handle_message; Telegram, Discord and
WebSocket updated to pass it.
Closes#3768
chengyongruandXubin Ren
4c4a9ae590