Added FastAPI server to handle file conversion to markdown

[dev-myk]

This PR introduces a FastAPI server that allows users to upload a file, which is then converted to Markdown using the Markitdown library.

What I Added:

• A new server.py file implementing a FastAPI-based API.
• A /convert endpoint that accepts file uploads and returns the Markdown conversion result.
• Integration of the Markitdown library to process file contents.

How It Works:

• Users send a POST request to /convert with a file as input.
• The server reads the file content and passes it to Markitdown for conversion.
• The API returns a JSON response containing the Markdown text.

[afourney]

Thanks. I've been thinking about something like this -- especially for MCP use. But I've not yet decided how to proceed. I think I might advocate for a separate package. Let me think about this a little.

[afourney]

There's now an mcp server

A more general FastAPI server would also be useful, perhaps. But I think I would recommend hosting that as a separate repo/project similar to how plugins are handled currently.