Enhancement: light-weight version working directly in-browser, server-less

[vadimkantorov]

FM can talk directly to GitHub API (via a user-provided PAT), and then be available without VS Code and without any server-side auth proxy.

At least, some basic version should be possible (front-matter visual editor, monaco editor for markdown content or some sort of MDX editor) - even having the front-matter metadata editor as a standalone React component would be great

For simple blogs or NGO websites, it could be sufficient

[estruyf]

This would also fix the following issue #161

Any interest to work on this @vadimkantorov?