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/design-lab/batchB.tsx

@@ -16,8 +16,8 @@ import {
   SlidersHorizontal,
   Tv,
   Users,
-  Youtube,
 } from "lucide-react";
+import { YouTubeIcon } from "../lib/brandIcons";
 import { Btn } from "./batchA";
 import { hexContrast, hueGap } from "../lib/colorMath";
 import { Reference, Sample } from "./labKit";
@@ -285,7 +285,7 @@ function WatchPage() {
 type NavDef = { icon: typeof Home; en: string; hu: string };
 const NAV: NavDef[] = [
   { icon: Home, en: "Home", hu: "Kezdőlap" },
-  { icon: Youtube, en: "Feed", hu: "Feed" },
+  { icon: YouTubeIcon, en: "Feed", hu: "Feed" },
   { icon: Tv, en: "Channels", hu: "Csatornák" },
   { icon: ListVideo, en: "Playlists", hu: "Listák" },
   { icon: Clapperboard, en: "Plex", hu: "Plex" },