docs: Document the public API

[velocitysystems]

This PR adds comprehensive documentation for the media-parser crate, detailing its capabilities and public API.
Key features:

• Retrieving metadata (title, artist, album, duration, etc.)
• Listing tracks with type, codec, and language
• Extracting subtitles by track ID or language
• Capturing single or multiple video thumbnails

[velocitysystems]

Reviewed with @polw1 and updated to include an additional API for retrieving metadata.

[velocitysystems]

@yokuze @onebytegone Added package.json and standardization.

[yokuze]

Thanks for all of the updates and for starting out with docs.

I think this is far as I can get in the review before some of the comments are addressed, esp. the one about moving some of the code into Rust files.

Also, please keep in mind that my review is limited to:

• Does this follow our coding standards?
• Does this make sense an API?
• Are there logical errors, missing info, etc.?

but since I do not have any information about our use cases for the library I cannot review at the level of:

• Does this API provide all the functionality we need? Should it do more / less / something different?
• Should we be doing this at all, or something else given our goals? (Probably it's fine, but again, I don't have enough context)

For that, we'll need a discussion with @jthomerson and others, and perhaps soon we can sync up and you can give me an overview of what use cases you know of.

[yokuze]

Some of my earlier comments may not be relevant after you added MD linting.

[velocitysystems]

Closing in favour of #7.