### What problem does this PR solve?
issue:
[Bug]: Agent component (HTTP Request) "'>' not supported between
instances of 'int' and 'NoneType'"
[#10096](https://github.com/infiniflow/ragflow/issues/10096)
Change:
When the Invoke class instantiates HtmlParser without providing the
chunk_token_num parameter, the value defaults to None, leading to a
comparison error with block_token_count.
This change sets the default chunk_token_num to 512 to prevent such
errors.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
Co-authored-by: BadwomanCraZY <511528396@qq.com>
### What problem does this PR solve?
add support for eml file parser
#1363
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: Zhedong Cen <cenzhedong2@126.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
