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/OnboardingWizard.tsx

@@ -2,7 +2,8 @@ import { useEffect, useId, useRef } from "react";
 import { Trans, useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { qk } from "../lib/queryKeys";
-import { AlertTriangle, Check, Loader2, RefreshCw, ShieldCheck, X, Youtube } from "lucide-react";
+import { AlertTriangle, Check, Loader2, RefreshCw, ShieldCheck, X } from "lucide-react";
+import { YouTubeIcon } from "../lib/brandIcons";
 import { api, type Me } from "../lib/api";
 import { beginGrant, endOnboarding } from "../lib/onboarding";
 import { Button } from "./ui/Button";
@@ -186,7 +187,7 @@ export default function OnboardingWizard({ me, onClose }: { me: Me; onClose: ()
           {step === "read" && (
             <>
               <div className="mx-auto mb-4 grid place-items-center w-12 h-12 rounded-2xl bg-accent/15 text-accent">
-                <Youtube className="w-6 h-6" />
+                <YouTubeIcon className="w-6 h-6" />
               </div>
               <h2 id={titleId} className="text-lg font-semibold">
                 {t("onboarding.read.title")}
@@ -199,7 +200,7 @@ export default function OnboardingWizard({ me, onClose }: { me: Me; onClose: ()
               </p>
               <ConsentHeadsUp />
               <div className="mt-5 flex flex-col gap-2">
-                <Button size="lg" icon={<Youtube />} onClick={() => beginGrant("read")}>
+                <Button size="lg" icon={<YouTubeIcon />} onClick={() => beginGrant("read")}>
                   {t("onboarding.read.connect")}
                 </Button>
                 <Button variant="ghost" size="md" onClick={close}>