This adds user identification fields that can be passed to Dify workflows:
- sender_id: the sender's ID (converted to string)
- sender_name: the sender's display name (from Friend.nickname or GroupMember.member_name)
Both variables are also available as legacy inputs:
- langbot_sender_id
- langbot_sender_name
Resolves the feature request to pass WeChat Work user info to Dify workflows.
Co-authored-by: RockChinQ <45992437+RockChinQ@users.noreply.github.com>