mod: show fullscreen action item

Closes #367

Signed-off-by: bggRGjQaUbCoE <githubaccount56556@proton.me>

lib/plugin/pl_player/controller.dart

@@ -254,6 +254,8 @@ class PlPlayerController {
   /// 弹幕开关
   Rx<bool> isOpenDanmu = false.obs;
 
+  late final showFSActionItem = GStorage.showFSActionItem;
+
   /// 弹幕权重
   int danmakuWeight = 0;
   int filterCount = 0;

lib/plugin/pl_player/widgets/app_bar_ani.dart

@@ -28,7 +28,7 @@ class AppBarAni extends StatelessWidget implements PreferredSizeWidget {
         parent: controller,
         curve: Curves.linear,
       )),
-      child: Container(
+      child: DecoratedBox(
         decoration: BoxDecoration(
           gradient: position! == 'top'
               ? const LinearGradient(