Migrate away from skeleton AppShell

[joshuata]

The skeleton AppShell component has been deprecated, and is responsible for many of the strange scrolling and navigation behaviors that have been reported including at least #183, #156, and #42 just from a quick check. This is because it scrolls only the main slot and not the full page. Skeleton themselves have a section in their documentation on why they have moved away from this solution: https://next.skeleton.dev/docs/get-started/layouts#using-body-scroll. Although this is for the upcoming release, the features to replace it are all just tailwind so it is all in place today.

In order to replace it we can start with the example for their two column layout. It should be a fairly quick swap, especially for someone with more css or tailwind experience than myself.

I'll start looking into the process myself, but any assistance would be welcome