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/Feed.tsx

@@ -19,9 +19,9 @@ import {
   RefreshCw,
   Rows3,
   Trash2,
-  Youtube,
   type LucideIcon,
 } from "lucide-react";
+import { YouTubeIcon } from "../lib/brandIcons";
 import { api, HttpError, type FeedFilters, type Video, type VideoStatus } from "../lib/api";
 import i18n from "../i18n";
 import { notifyActionError } from "../lib/actionErrors";
@@ -352,7 +352,7 @@ export default function Feed({
   // The toast's Undo action re-enters onState, which is a forward reference to the binding still
   // being defined — the same shape PlexPlayer's session reclaim has, and answered the same way.
   const onStateRef = useRef(onState);
-  // eslint-disable-next-line react-hooks/immutability
+  // eslint-disable-next-line react-hooks/immutability -- a latest-value ref for a forward reference: the Undo re-enters onState before its binding exists
   onStateRef.current = onState;
 
   const onResetState = useCallback(
@@ -473,7 +473,7 @@ export default function Feed({
               {t("feed.yt.back")}
             </Button>
             <span className="mx-1 h-5 w-px bg-border" aria-hidden="true" />
-            <Youtube className="w-4 h-4 text-accent shrink-0" />
+            <YouTubeIcon className="w-4 h-4 text-accent shrink-0" />
             <span className="text-sm font-semibold truncate">
               {t("feed.yt.resultsFor", { query: ytSearch })}
             </span>
@@ -882,7 +882,7 @@ export default function Feed({
           {filters.q.trim() && !isDemo && (
             <Button
               className="mt-4"
-              icon={<Youtube />}
+              icon={<YouTubeIcon />}
               onClick={() => onYtSearch(filters.q.trim())}
             >
               {t("feed.yt.searchFor", { query: filters.q.trim() })}