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/components/PlayerModal.tsx

@@ -70,6 +70,7 @@ import {
   useYtBigView,
   useYtProgress,
   useYtVolume,
+  YT_API_LOAD_FAILED,
 } from "../lib/playerModalHooks";
 import { useScrollFade } from "../lib/useScrollFade";
 import { Button } from "./ui/Button";
@@ -372,6 +373,7 @@ export default function PlayerModal({
     const victim = active;
     removingRef.current = true;
     let done = false;
+    // eslint-disable-next-line react-hooks/todo -- the React Compiler cannot lower try without catch yet, so the enclosing component or hook stays uncompiled; pinned in compilerCoverage, burned down in E32 S3
     try {
       done = await onRemoveFromList(victim);
     } finally {
@@ -831,9 +833,11 @@ export default function PlayerModal({
                   <AlertTriangle className="w-8 h-8 text-warn mx-auto mb-3" />
                   <h3 className="text-base font-semibold">{t("player.unavailableTitle")}</h3>
                   <p className="text-sm text-muted mt-1.5 mb-4">
-                    {playerError === 101 || playerError === 150
-                      ? t("player.embedDisabledBody")
-                      : t("player.unavailableBody")}
+                    {playerError === YT_API_LOAD_FAILED
+                      ? t("player.apiLoadFailedBody")
+                      : playerError === 101 || playerError === 150
+                        ? t("player.embedDisabledBody")
+                        : t("player.unavailableBody")}
                   </p>
                   <LinkButton
                     href={`https://www.youtube.com/watch?v=${currentVideoId}`}