- Add RingCentral channel plugin with WebSocket subscription support
- Implement JWT authentication via @ringcentral/sdk
- Support DM and group messaging with mention gating
- Add credential file support (rc-credentials.json)
- Implement full ChannelPlugin interface (pairing, security, messaging, etc.)
- Add .gitignore entries for credential files
Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>
