chore: set the minimum windows size to 640

Author: LucasXu0

frontend/appflowy_flutter/lib/startup/tasks/app_window_size_manager.dart

@@ -7,7 +7,7 @@ import 'package:appflowy/startup/startup.dart';
 
 class WindowSizeManager {
   static const double minWindowHeight = 640.0;
-  static const double minWindowWidth = 960.0;
+  static const double minWindowWidth = 640.0;
   // Preventing failed assertion due to Texture Descriptor Validation
   static const double maxWindowHeight = 8192.0;
   static const double maxWindowWidth = 8192.0;
@@ -35,7 +35,10 @@ class WindowSizeManager {
 
   Future<Size> getSize() async {
     final defaultWindowSize = jsonEncode(
-      {WindowSizeManager.height: minWindowHeight, WindowSizeManager.width: minWindowWidth},
+      {
+        WindowSizeManager.height: minWindowHeight,
+        WindowSizeManager.width: minWindowWidth,
+      },
     );
     final windowSize = await getIt<KeyValueStorage>().get(KVKeys.windowSize);
     final size = json.decode(