feat(player): open YouTube's native settings menu fully + push higher quality

The transparent interaction overlay (click=play/pause, wheel=volume, keeps
keyboard focus off the cross-origin iframe) also blocked YouTube's own settings
menu, which expands down over the video past the overlay: items below the first
few were unclickable, and 'More options' made it worse.

Now the overlay yields to native controls. Clicking a native control (gear/seek/
CC) moves focus into the player iframe — the only cross-origin signal available —
which we detect (window blur + getIframe() focus check) to drop the overlay's
pointer-events, so the whole menu is navigable at any height. A discreet badge
signals native mode; moving the pointer off the video (or the window regaining
focus) re-arms the click/scroll/keyboard shortcuts.

Quality: the IFrame API's setPlaybackQuality/suggestedQuality are hard no-ops now,
so the real lever is the rendered player size — bump the modal max-w-4xl -> 6xl so
YouTube's ABR targets a higher resolution — plus a best-effort 'vq=hd1080' URL hint.
i18n (en/hu/de) for the native-mode badge.

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

@@ -35,5 +35,6 @@
   "unavailableBody": "This video isn't available — it may be private, removed, or region-restricted.",
   "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: volume · F: fullscreen"
+  "shortcutsHint": "Click: play/pause · Scroll: volume · F: fullscreen",
+  "nativeControls": "YouTube controls active"
 }