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/ui/AnchoredPopover.tsx

@@ -96,7 +96,9 @@ type ItemRole = "menuitem" | "menuitemradio" | "menuitemcheckbox" | "option";
 // EXCEPTION: a menu whose SELECTED item paints its OWN row background (a solid bg-accent — the
 // table-filter options) passes `keepSelectedPaint`, so the highlight yields to ring-only there; a fill
 // would downgrade that solid paint to a 35% tint (the R9 concern, now scoped to just that idiom).
-const HIGHLIGHT_UNSELECTED =
+// Exported as ROVING_HIGHLIGHT for a listbox that is not a PopoverItem (the command palette, the Plex
+// typeahead): the row carries `data-active` and takes this, so the keyboard row looks the same everywhere.
+export const ROVING_HIGHLIGHT =
   "data-active:bg-accent/35 data-active:text-fg data-active:ring-1 data-active:ring-inset data-active:ring-accent/60";
 const HIGHLIGHT_SELECTED =
   "data-active:bg-accent/35 data-active:text-fg data-active:ring-2 data-active:ring-inset data-active:ring-accent/80";
@@ -214,7 +216,7 @@ export function PopoverItem({
           ? keepSelectedPaint
             ? HIGHLIGHT_SELECTED_RING_ONLY
             : HIGHLIGHT_SELECTED
-          : HIGHLIGHT_UNSELECTED
+          : ROVING_HIGHLIGHT
       }${className ? ` ${className}` : ""}`}
     >
       {children}