[Feature]: Support for documenting multipart req/res

[PENEKhun]

Currently, itdoc does not seem to have native support for documenting APIs that use multipart/form-data (e.g., file uploads combined with JSON fields).

It would be useful if itdoc could:

Allow defining multipart request bodies with mixed types (files + text fields).

Generate examples in the final documentation that clearly show how clients should construct multipart requests.

Optionally, support multipart responses if applicable.

This is a fairly common use case (especially for file uploads), and having first-class support in itdoc would make the generated API docs much clearer and more complete.

TODO

• binary body when request
• multipart/form-data
• response file