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/playerModalHooks.progress.dom.test.tsx

@@ -12,7 +12,7 @@
 import { describe, it, expect, vi, afterEach } from "vitest";
 import { renderHook } from "@testing-library/react";
 import { QueryClient } from "@tanstack/react-query";
-import { createRef, type MutableRefObject } from "react";
+import { createRef, type RefObject } from "react";
 import { useYtProgress } from "./playerModalHooks";
 import { patchCachedProgress } from "./progressCache";
 import { qk } from "./queryKeys";
@@ -73,7 +73,7 @@ function mountPlayer(qc: QueryClient, sessionPos: Map<string, number>) {
       activeId: VID,
       resumeAt: 748,
       mountRef: { current: mount },
-      playerRef: createRef<YTPlayer>() as MutableRefObject<YTPlayer | null>,
+      playerRef: createRef<YTPlayer>() as RefObject<YTPlayer | null>,
       currentIdRef: { current: VID },
       navRef: { current: { queue: undefined, index: 0 } },
       modeRef: { current: { autoMode: "off", loopMode: "off" } },