Extract the manage/reorder-libraries sheet from the libraries screen into
a shared widget with a public launcher, and add a settings tile (top
group, gated on having libraries) that opens it. The libraries screen
keeps its side-nav refresh and re-select-on-hide behavior via launcher
hooks; the TV dialog path lives in the launcher so the entry works there
too.
Desktop overlay sheets defaulted to a fixed 400px max height, which left
the reorder sheet ~280px tall. Both default-constraint sites now use 75%
of window height, matching mobile.
close#1468