fix(plex): the player's ⋯ and tracks lists are real menus, and every close returns the focus

They were hand-built divs: no menu roles, no arrow keys, and Escape left the
focus on <body>. Both run on the popover engine now (media-tone rows), and the
tuning panel is a labelled dialog that takes the focus and hands it back to ⋯.

frontend/src/components/PlexPlayerSettings.tsx

@@ -1,4 +1,4 @@
-import { type RefObject } from "react";
+import { useLayoutEffect, type RefObject } from "react";
 import { useTranslation } from "react-i18next";
 
 import { Slider, Toggle } from "./plexPlayerControls";
@@ -18,6 +18,9 @@ export function PlexPlayerSettings(props: {
   // which is the honest shape — the element is null until the div mounts. The old `RefObject<T>` lied
   // about that and 18's types let it.
   menuRef: RefObject<HTMLDivElement | null>;
+  /** The ⋯ that opened the panel: the focus goes back to it when the panel closes with the focus
+   *  inside — by Escape, Back or the ⋯ itself — instead of falling to <body> (E28 review D3). */
+  returnFocusTo: RefObject<HTMLElement | null>;
   settingsTabs: { key: SettingsTab; label: string }[];
   activeTab: SettingsTab;
   setSettingsTab: (tab: SettingsTab) => void;
@@ -28,6 +31,7 @@ export function PlexPlayerSettings(props: {
 }) {
   const {
     menuRef,
+    returnFocusTo,
     settingsTabs,
     activeTab,
     setSettingsTab,
@@ -37,9 +41,23 @@ export function PlexPlayerSettings(props: {
     now,
   } = props;
   const { t } = useTranslation();
+  // Into the panel on open (its first tab), and back to the ⋯ on close. The cleanup runs while the
+  // panel is still in the DOM, so "the focus was inside" is read before its removal drops it to
+  // <body>; focus the reader moved elsewhere (a click on the video) stays where they put it.
+  useLayoutEffect(() => {
+    const panel = menuRef.current;
+    const back = returnFocusTo.current; // the ⋯ outlives the panel: it is the panel's own trigger
+    panel?.querySelector<HTMLElement>("button")?.focus({ preventScroll: true });
+    return () => {
+      if (panel?.contains(document.activeElement))
+        queueMicrotask(() => back?.focus({ preventScroll: true }));
+    };
+  }, [menuRef, returnFocusTo]);
   return (
     <div
       ref={menuRef}
+      role="dialog"
+      aria-label={t("plex.player.settings")}
       onWheel={(e) => e.stopPropagation()}
       onClick={(e) => e.stopPropagation()}
       className="border border-white/15 bg-media-chrome/95 absolute bottom-full right-0 z-menu mb-2 w-80 rounded-xl p-2 text-sm text-white shadow-2xl"