Consider changing UI to run in web browser

[holly-hacker]

Rather than using eframe to run the download and hax UI as a native window, run the hax ui as a browser page and the download ui in the terminal.

This has the following benefits:

• There don't need to be any dependencies on window creation libraries (assuming webview is also skipped, Allow running as server only (no webview) #6)
• Users can control the hax from their phones
• We can support Wayland users (see Allow running on wayland #4)

[holly-hacker]

An additional benefit is that we can get rid of the outdated tauri-egui integration, which is causing #15. We cannot resolve that issue without forking the project or getting rid of the dependency.