WIP: Rework mobile navigation

The current filter based approach of the sidebar is a good for widescreen and on desktop. However, on mobile it becomes quite confusing imo to have to navigate using such a dense sidebar. I am proposing adding a bottom navigation bar (only on mobile) in order for it to be easy for users to distinguish photos views, folder views, and stuff they've tagged/favourited.

This has some issues right now because there isn't a page that is just "photos", without any time filters or anything, and so currently it just dumps you on the years filter page.