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/i18n/locales/en/player.json

@@ -34,6 +34,7 @@
   "playInApp": "Play in the in-app player",
   "unavailableTitle": "Can't play this here",
   "unavailableBody": "This video isn't available — it may be private, removed, or region-restricted.",
+  "apiLoadFailedBody": "The YouTube player didn't load — a connection problem or a content blocker may be stopping it. It still plays on YouTube.",
   "embedDisabledBody": "The owner disabled playback on other sites (common for auto-generated “Topic” music tracks). It still plays on YouTube.",
   "openOnYoutube": "Open on YouTube",
   "shortcutsHint": "Click: play/pause · Scroll or ↑ ↓: volume · F: fill the window",

frontend/src/i18n/locales/hu/player.json

@@ -34,6 +34,7 @@
   "playInApp": "Lejátszás a beépített lejátszóban",
   "unavailableTitle": "Ez itt nem játszható le",
   "unavailableBody": "Ez a videó nem elérhető — lehet privát, eltávolított vagy régiókorlátozott.",
+  "apiLoadFailedBody": "A YouTube-lejátszó nem töltődött be — kapcsolati hiba vagy tartalomblokkoló akadályozhatja. A YouTube-on viszont lejátszható.",
   "embedDisabledBody": "A tulajdonos letiltotta a lejátszást más oldalakon (gyakori az automatikusan generált „Topic” zenei sávoknál). A YouTube-on viszont lejátszható.",
   "openOnYoutube": "Megnyitás YouTube-on",
   "shortcutsHint": "Kattintás: lejátszás/szünet · Görgő vagy ↑ ↓: hangerő · F: teljes ablak",