build(frontend): close the lint gaps the E32 audit measured

eslint now also enforces:
- the React Compiler diagnostics that `recommended` leaves out (todo,
  memo-dependencies and ten zero-hit tripwires);
- a description on every suppression, and no blanket disables;
- no focused or skipped tests (vitest and playwright);
- the typed pair no-floating-promises and no-deprecated.

Lint also covers e2e/ and the TypeScript build configs, which `eslint .`
had been skipping in silence.

Every hit is fixed or suppressed inline with a named reason:
- The 31 try statements the compiler cannot lower yet carry a suppression
  until S3 rewrites them. Five other compiler skips were plain fixes:
  a module counter bumped inside a hook, a ref read in a default
  parameter, and a local named like the <section> it renders.
- The real defects behind floating promises are fixed. ChatDock threw at
  nobody when the device key store could not be opened. VideoEditor's
  play() rejection went unhandled. loadYouTubeApi never rejected, so a
  blocked IFrame API left the player on an empty stage forever; it now
  fails on a script error or after 15 s, shows its own error with the
  way out, and lets the next open try again.
- MutableRefObject, FormEvent and lucide's deprecated brand icon are
  replaced. The YouTube glyph now lives in lib/brandIcons.
- The lint-probe harness lets its virtual file names into TypeScript's
  default project, so the contract tests still run the real config.

frontend/src/lib/plexPlayerHooks.controls.dom.test.tsx

@@ -26,7 +26,9 @@ describe("useControlsVisibility", () => {
   it("hides 3 s after the last activity while playing", () => {
     const { result } = setup();
     act(() => result.current.wake());
-    act(() => vi.advanceTimersByTime(3000));
+    act(() => {
+      vi.advanceTimersByTime(3000);
+    });
     expect(result.current.uiVisible).toBe(false);
   });
 
@@ -36,16 +38,45 @@ describe("useControlsVisibility", () => {
       result.current.wake();
       result.current.holdOnHover(true);
     });
-    act(() => vi.advanceTimersByTime(10_000));
+    act(() => {
+      vi.advanceTimersByTime(10_000);
+    });
     expect(result.current.uiVisible).toBe(true);
 
     act(() => result.current.holdOnHover(false));
-    act(() => vi.advanceTimersByTime(2900));
+    act(() => {
+      vi.advanceTimersByTime(2900);
+    });
     expect(result.current.uiVisible).toBe(true); // a fresh 3 s from the leave, not from the wake
-    act(() => vi.advanceTimersByTime(100));
+    act(() => {
+      vi.advanceTimersByTime(100);
+    });
     expect(result.current.uiVisible).toBe(false);
   });
 
+  // E28 E6 / round 2 P4: a keyboard focus in the chrome holds the bar — but only for FOCUS_HOLD_MS
+  // after the last key, not for the whole film. The 3 s timer finds the hold, re-arms for what is
+  // left of it, and hides once it is over (E32 rewrote that re-arm without recursion).
+  it("holds for a keyboard focus until 10 s after the last key, then hides", () => {
+    const { result } = setup();
+    act(() => {
+      result.current.holdOnFocus(true);
+      result.current.wake();
+    });
+    act(() => {
+      vi.advanceTimersByTime(3000);
+    });
+    expect(result.current.uiVisible).toBe(true); // the hold, not the 3 s
+    act(() => {
+      vi.advanceTimersByTime(6900);
+    });
+    expect(result.current.uiVisible).toBe(true); // 9.9 s after the key
+    act(() => {
+      vi.advanceTimersByTime(100);
+    });
+    expect(result.current.uiVisible).toBe(false); // the hold is over, focus or not
+  });
+
   // C3: on touch nothing moves a mouse, so a tap toggles the bar and playback arms the timer.
   it("toggle hides a shown bar at once and shows a hidden one", () => {
     const { result } = setup();