🐛 Fix bugs on windows

lib/shells/system_shell.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:rhythm_box/platform.dart';
+import 'package:window_manager/window_manager.dart';
 
 class SystemShell extends StatelessWidget {
   final Widget child;
@@ -8,19 +9,21 @@ class SystemShell extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    if (PlatformInfo.isMacOS) {
-      return Column(
-        children: [
-          Container(
-            height: 28,
-            color: Theme.of(context).colorScheme.surface,
-          ),
-          const Divider(
-            thickness: 0.3,
-            height: 0.3,
-          ),
-          Expanded(child: child),
-        ],
+    if (PlatformInfo.isDesktop) {
+      return DragToMoveArea(
+        child: Column(
+          children: [
+            Container(
+              height: 28,
+              color: Theme.of(context).colorScheme.surface,
+            ),
+            const Divider(
+              thickness: 0.3,
+              height: 0.3,
+            ),
+            Expanded(child: child),
+          ],
+        ),
       );
     }