fix(design): rating and live colour tokens, the player's menus over its notices, the info overlay on a light theme (E28)

- F16: --rating (theme-scoped gold, 4.5:1 on the page and its chip), --rating-media, --live/--live-fg,
  --media-chrome replace 14 palette literals; a lint rule refuses palette classes; the theme contract
  measures them.
- The Plex player's notices drew over its open settings/tracks popovers: notices z-base, popovers z-menu.
- The player's info overlay rendered theme tokens on its always-dark panel: on a light theme the score
  (2.6:1), collection years (3.2:1) and cast initials (1.05:1) were unreadable; onDark variants now.
- The lint-rule contract tests share one ESLint with a one-off warm-up (a cold first lint took 8 s,
  past vitest's 5 s).

frontend/src/components/PlexPlayer.tsx

@@ -1183,9 +1183,10 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
           first. Until then the <track> is deliberately NOT mounted, and this says why instead of
           leaving the viewer to conclude that switching subtitles "does nothing" (bug hunt 2026-09,
           item 8). A failure is said even over a mounted window (see `subNotice`). It sits one rung
-          above the track-switch OSD so the two never overlap. */}
+          above the track-switch OSD so the two never overlap. Both notices are `z-base`, under the
+          settings and tracks popovers (`z-menu`): an open menu is never drawn over (E28 audit). */}
       <div
-        className="pointer-events-none absolute inset-x-0 bottom-36 z-menu flex justify-center px-4"
+        className="pointer-events-none absolute inset-x-0 bottom-36 z-base flex justify-center px-4"
         aria-live="polite"
       >
         {selectedSub && subNotice && (
@@ -1211,7 +1212,7 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
           conditioning the wrapper re-created it for every switch, not just the first (E10 review
           round 1). Toaster.tsx carries the same rule and the same shape. */}
       <div
-        className="pointer-events-none absolute inset-x-0 bottom-24 z-menu flex justify-center px-4"
+        className="pointer-events-none absolute inset-x-0 bottom-24 z-base flex justify-center px-4"
         aria-live="polite"
       >
         {osd && (
@@ -1499,7 +1500,7 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
                     style={tracksFade.style}
                     onClick={(e) => e.stopPropagation()}
                     onWheel={(e) => e.stopPropagation()}
-                    className="border border-white/15 bg-neutral-900/95 absolute bottom-full right-0 mb-2 w-56 max-h-[60vh] overflow-auto no-scrollbar rounded-xl p-2 text-sm text-white shadow-2xl"
+                    className="border border-white/15 bg-media-chrome/95 absolute bottom-full right-0 z-menu mb-2 w-56 max-h-[60vh] overflow-auto no-scrollbar rounded-xl p-2 text-sm text-white shadow-2xl"
                   >
                     {detail.audio_streams.length > 1 && (
                       <>
@@ -1641,7 +1642,7 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
           }}
         >
           <div
-            className="my-auto w-full max-w-3xl rounded-2xl border border-white/15 bg-neutral-900/95 shadow-2xl"
+            className="my-auto w-full max-w-3xl rounded-2xl border border-white/15 bg-media-chrome/95 shadow-2xl"
             onClick={(e) => e.stopPropagation()}
           >
             <Suspense fallback={null}>