The header's pills now arrive by portal after the shell has mounted, so the shell's one synchronous
measurement saw an empty header, and the ResizeObserver brought `--hdr-h` up a frame or more later:
meanwhile the content sat under the pills (the feed toolbar jumped 55px on a tablet; e2e caught it).
The measurement re-runs before paint whenever what fills the header changes.
The header used to pick its pills by `page === …` and import five module controls, and Plex's
Discover/Browse toggle needed a context bridge to reach the sub-view that lives in PlexBrowse.
Now the header is an empty band: PageShell hands its root box out as a slot, a page portals its
own pills into it (PageHeader), and the palette's Jump-to pill shows where no page does
(PageHeaderDefault, rendered inside the page's Suspense so a loading page shows no stand-in).
Plex's toggles take the sub-view as a prop; PlexViewBridge and its context are gone, and with
them the header's five layer suppressions.
No visible change: every header pill's box measured identical against the previous build on eight
pages, in Hungarian and English.
peter