Better tracklist rendering performance

[oskarrough]

As soon as you render more than ~200 tracks you feel the browser freezing on an M2 MacBook. This is primarily due to 1) the amount of javascript work each <r4-track> and its child components do, and 2) the CSS layout for so many elements.

This PR

• conditionally renders the dialogs inside r4-track, only when the menu is actually open (this makes the difference)
• uses content:visibility css trick on r4-list-item to allow the browser to optimize rendering depending on viewport

The branch also touches on the query, filter and search components to eliminate double-fetching.

[oskarrough]

The mention and tag links on r4-track no longer work well with the query url stuff. HMMMMM

[oskarrough]

Meh can't figure this filter query url params stuff out for now. Closing in favour of #176