fix(ui): move game-screen close button to its own top row (was overlapping HUD)

On device the floating top-left X (48px IconButton) overlapped the HUD moves
chip. Move it into the column flow above the HUD, left-aligned, so it never
collides. Found via on-device test build.

lib/ui/screens/game_screen.dart

@@ -256,6 +256,18 @@ class _GameScreenState extends ConsumerState<GameScreen>
                   padding: const EdgeInsets.all(16),
                   child: Column(
                     children: [
+                      // Close/back sits on its own top row so it never overlaps
+                      // the HUD's moves chip (which lives at the top-left).
+                      if (Navigator.of(context).canPop())
+                        Align(
+                          alignment: Alignment.centerLeft,
+                          child: IconButton(
+                            padding: EdgeInsets.zero,
+                            visualDensity: VisualDensity.compact,
+                            icon: const Icon(Icons.close, color: Colors.white54),
+                            onPressed: () => Navigator.of(context).pop(),
+                          ),
+                        ),
                       HudWidget(view: view),
                       Expanded(
                         child: Center(
@@ -308,15 +320,6 @@ class _GameScreenState extends ConsumerState<GameScreen>
                           ref.read(tutorialProvider.notifier).dismissHud(),
                     ),
                   ),
-                if (Navigator.of(context).canPop())
-                  Positioned(
-                    top: 4,
-                    left: 4,
-                    child: IconButton(
-                      icon: const Icon(Icons.close, color: Colors.white54),
-                      onPressed: () => Navigator.of(context).pop(),
-                    ),
-                  ),
               ],
             ),
           ),