Bring the Plex module's filter surface in line with the feed's final shape:
- Flatten the rail: PlexSidebar passes `collapsible={false}` to FilterRail so
the widgets become plain always-open label + control rows (no collapse
chevrons; reorder/hide in edit mode stay). Drop the rail's own "Clear all" —
the chip row above the grid already owns it.
- Move Sort + the Discover/Browse toggle into the applied-filter chip row,
pinned right directly above the grid (a `sortView` fragment, like the feed's),
and give ActiveFilterChips `flex-1` so it gets the shared responsive overflow
(wide: fit + "+N" pill; narrow: single "N filters" count pill) — the chips can
no longer crowd the controls off-screen.
ItemCount leads its own toolbar row, matching the feed. No behaviour change to
Discover, which keeps its standalone view toggle.