Add double-click functionality to ChannelPlayer for fullscreen toggle: enhance user interaction by allowing users to enter fullscreen mode with a double-click on the player.

frontend/src/features/streaming/ChannelPlayer.tsx

@@ -118,6 +118,7 @@ export function ChannelPlayer({
         muted
         className="h-full w-full"
         onClick={togglePlay}
+        onDoubleClick={toggleFullscreen}
         onPlay={() => setPlaying(true)}
         onPause={() => setPlaying(false)}
       />