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/lib/pxBox.contract.test.ts

@@ -1,14 +1,11 @@
-import { fileURLToPath } from "node:url";
-
-import { ESLint } from "eslint";
 import { describe, expect, it } from "vitest";
 
+import { eslint } from "./lintProbe.testkit";
+
 // The px-frozen BOX rule in eslint.config.js (beside the older `text-[Npx]` one). A `no-restricted-
 // syntax` selector that matches nothing looks exactly like a clean codebase, so pin that it fires.
-const FRONTEND = fileURLToPath(new URL("../../", import.meta.url));
 
 async function refused(source: string): Promise<number> {
-  const eslint = new ESLint({ cwd: FRONTEND });
   const [result] = await eslint.lintText(source, { filePath: "src/components/__probe.tsx" });
   return (result?.messages ?? []).filter((m) => m.message.startsWith("px-frozen box size")).length;
 }
@@ -26,7 +23,6 @@ describe("a px-frozen box utility", () => {
   it("is refused with a fractional size, for a box and for a font", async () => {
     const px = (u: string, n: number) => `${u}-[${n}px]`;
     expect(await refused(`export const e = "${px("w", 12.5)}";\n`)).toBe(1);
-    const eslint = new ESLint({ cwd: FRONTEND });
     const [font] = await eslint.lintText(`export const f = "${px("text", 9.5)}";\n`, {
       filePath: "src/components/__probe.tsx",
     });