feat(tv): implement fullscreen navigation behavior for TV page

k-tv-frontend/app/(main)/tv/page.tsx

@@ -79,6 +79,14 @@ export default function TvPage() {
     document.addEventListener("fullscreenchange", handler);
     return () => document.removeEventListener("fullscreenchange", handler);
   }, []);
+
+  // Hide the shared nav bar in fullscreen; reveal it when overlays are shown
+  // (mouse move / key press). Classes are cleaned up on unmount.
+  useEffect(() => {
+    document.body.classList.toggle("tv-fullscreen", isFullscreen);
+    document.body.classList.toggle("tv-overlays", isFullscreen && showOverlays);
+    return () => document.body.classList.remove("tv-fullscreen", "tv-overlays");
+  }, [isFullscreen, showOverlays]);
   const toggleFullscreen = useCallback(() => {
     if (!document.fullscreenElement) {
       document.documentElement.requestFullscreen().catch(() => {});

k-tv-frontend/app/globals.css

@@ -127,3 +127,16 @@
     @apply font-sans;
   }
 }
+
+/* Hide the nav bar when the TV page is in fullscreen, reveal on interaction */
+body.tv-fullscreen header {
+  transform: translateY(-100%);
+  opacity: 0;
+  pointer-events: none;
+  transition: transform 0.25s ease, opacity 0.25s ease;
+}
+body.tv-fullscreen.tv-overlays header {
+  transform: translateY(0);
+  opacity: 1;
+  pointer-events: auto;
+}