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/controlRules.contract.test.ts

@@ -1,15 +1,12 @@
-import { fileURLToPath } from "node:url";
-
-import { ESLint } from "eslint";
 import { describe, expect, it } from "vitest";
 
+import { eslint } from "./lintProbe.testkit";
+
 // Two lint rules about controls: no native <select> (the canonical "FE control" row in CLAUDE.md;
 // six had drifted in before the rule existed), and no hover gated on `enabled:` alone. A selector
 // that matches nothing looks exactly like a clean codebase, so this pins that each 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("No native <select>")).length;
 }
@@ -25,7 +22,6 @@ describe("a native select", () => {
 // which then lit up on hover as if a click would work.
 describe("a hover gated on `enabled:` alone", () => {
   it("is refused; the aria-aware gate is not", async () => {
-    const eslint = new ESLint({ cwd: FRONTEND });
     const lint = async (cls: string) =>
       (
         await eslint.lintText(