The scan/opening/status/error lines, offline mode and its retry, pinning a
collection offline, the sync and thumbnail-sweep state, and the callbacks
that route the grid to a rescan, a sync, another library, a panorama merge
or an export — the last of what AppWindow still carried under the
library- prefix — move onto the `Library` global started earlier on this
branch. Rust reaches them through window.global::<Library>() rather than
window.set_/get_/on_/invoke_ on the root.
library-visible is the one name that stays: it is computed from
active-page and active-view, the shell's own routing state, which a
global cannot read. AppWindow now declares no other library- property or
callback.
dtourolle
1e472fd251