remove landscape top-edge gesture barrier causing black bar on iPad

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/screens/channel/chat/chat.dart

@@ -109,19 +109,6 @@ class Chat extends StatelessWidget {
                       ),
                     ),
                   ),
-                  // Prevents accidental chat scrolling when swiping down from the top edge
-                  // to access system UI (Notification Center/Control Center) in landscape mode.
-                  if (context.isLandscape)
-                    Positioned(
-                      top: 0,
-                      left: 0,
-                      right: 0,
-                      height: 24,
-                      child: GestureDetector(
-                        behavior: HitTestBehavior.translucent,
-                        onVerticalDragStart: (_) {},
-                      ),
-                    ),
                   Positioned(
                     left: 0,
                     right: 0,