Deep links into specific path in .nar

[wh0]

Have an extra url parameter and, after things load, expand down to that path. Scroll it into view too maybe.

Or it might be easier to know to expand it as we build the tree? We currently have some code to make it lazily fill in a directory's entries when the user first expands it: https://github.com/wh0/nix-cache-view/blob/1a5bba2d55272506ff2f7c6af27cf0bf92d79474/nar.html#L52

[wh0]

let's have it expand everything right off the bat, how big do nix packages tend to be anyway