Send a message or file to the Feishu chat that initiated this session.

Use this tool to proactively push text messages or files (images, PDFs, PPTs, etc.) to the user's Feishu chat.

Supported file types for upload:
- Images: png, jpg, jpeg, gif, bmp, webp
- Documents: pdf, doc, docx, xls, xlsx, ppt, pptx
- Media: opus, mp4
- Other: any file (sent as stream)

You must provide at least one of `text` or `file_path`.
