Fixes#6294
QQ official bot receives emoji/sticker messages as raw XML-like tags:
`<faceType=4,faceId="",ext="eyJ0ZXh0IjoiW+a7oeWktOmXruWPt10ifQ==">`
This made the LLM unable to understand the emoji content.
Changes:
- Added `_parse_face_message()` method to parse face message format
- Decode base64 `ext` field to get emoji description text
- Replace face tags with `[表情:描述]` format for readability
Example:
- Input: `<faceType=4,faceId="",ext="eyJ0ZXh0IjoiW+a7oeWktOmXruWPt10ifQ==">`
- Output: `[表情:[满头问号]]`
Co-authored-by: ccsang <ccsang@users.noreply.github.com>