feat(plex): S3 toolbar relocation — scope to header, sort above the cards

Move the two "what am I browsing" controls out of the filter sidebar to where
they're always in reach, matching the Feed's layout:

- Library scope (both/movie/show) → a compact SegmentedToggle in the header next
  to the search box (new PlexScopeToggle, reads the same provider state).
- Sort → a SortControl in the row above the cards (into the PageToolbar band,
  count on the left, sort on the right), like the Feed.

Sidebar cleanup: drop the `scope` and `sort` island cards; the panel badge now
counts only the filters still in the panel (expanded filters + watch-state);
remove the now-unused sort imports. panelLayout drops both from the default plex
order (stale saved-layout keys are auto-filtered, so existing layouts degrade
cleanly). usePlexActiveFilters no longer emits a sort chip — sort is an
always-visible control now, not a removable narrowing (same as the Feed).

FE-only, no backend/migration. typecheck + eslint clean; 171 vitest green;
self-E2E verified (header scope drives the grid, sort control reorders, sidebar
no longer shows the two cards, no sort chip).

frontend/src/components/Header.tsx

@@ -6,6 +6,7 @@ import { moduleLabelKey, moduleOrder, stepModule } from "../lib/modules";
 import ModuleName from "./ModuleName";
 import SearchBar from "./SearchBar";
 import PlexSearchBox from "./PlexSearchBox";
+import PlexScopeToggle from "./PlexScopeToggle";
 import SyncStatus from "./SyncStatus";
 import { useNavigation, useNavigationActions } from "./NavigationProvider";
 import { useFeedFilters, useFeedFiltersActions } from "./FeedFiltersProvider";
@@ -103,6 +104,9 @@ export default function Header({
         canNext={multiModule}
       />
       {search}
+      {/* Library scope (movie/show/both) sits right of the search box on Plex — relocated here from
+          the filter sidebar (S3) so the primary "what am I browsing" control is always in reach. */}
+      {page === "plex" && me.plex_enabled && <PlexScopeToggle />}
       {/* Per-user sync status — it used to cost the nav rail a whole block. It sits with the other
           pills rather than pinned to the far right: on a wide window that just strands it. Only on
           the two modules it says anything about: the feed those subscriptions fill, and the manager