fix(design): the command palette's active row takes the menus' roving highlight, not an invisible bg-card; the Plex typeahead's hand copy of it goes (E28)

The palette row was ~1.07:1 on its glass (B3 names bg-card hovers a violation). ROVING_HIGHLIGHT is
exported from AnchoredPopover for the listboxes that are not PopoverItems; a contract holds that no file
paints the fill itself and every hand-built option row takes the recipe.

frontend/src/components/PlexSearchBox.tsx

@@ -11,6 +11,7 @@ import { useDebounced } from "../lib/useDebounced";
 import { availablePlexFields, healPlexField, plexFieldLabelKey } from "../lib/plexSearch";
 import { Pressable } from "./ui/Pressable";
 import { SURFACE } from "./ui/surfaces";
+import { ROVING_HIGHLIGHT } from "./ui/AnchoredPopover";
 
 // The Plex header search box: the shared SearchBar enriched with the S2 search scope-pill (a
 // GitHub-style field selector inside the box) and an instant typeahead of the top matches attached
@@ -156,10 +157,9 @@ export default function PlexSearchBox() {
                 onMouseEnter={() => setHi(i)}
                 onClick={() => pick(i)}
                 // The pointer moves `hi` too, so the highlight IS the hover: the menus' roving
-                // recipe (AnchoredPopover's HIGHLIGHT_UNSELECTED), one look for the mouse and the keys.
-                className={`flex w-full items-center gap-3 rounded-lg p-1.5 transition ${
-                  hi === i ? "bg-accent/35 text-fg ring-1 ring-inset ring-accent/60" : ""
-                }`}
+                // recipe (AnchoredPopover's ROVING_HIGHLIGHT), one look for the mouse and the keys.
+                data-active={hi === i ? "true" : undefined}
+                className={`flex w-full items-center gap-3 rounded-lg p-1.5 transition ${ROVING_HIGHLIGHT}`}
               >
                 <img
                   src={c.thumb}