fix(player): 增加退出清屏浮动按钮

lib/pages/player/widgets/exit_clear_screen_button.dart

@@ -0,0 +1,34 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/material.dart';
+
+/// Shared floating action used to leave clear-screen mode.
+class ExitClearScreenButton extends StatelessWidget {
+  const ExitClearScreenButton({
+    super.key,
+    required this.tooltip,
+    required this.onPressed,
+  });
+
+  final String tooltip;
+  final VoidCallback onPressed;
+
+  @override
+  Widget build(BuildContext context) {
+    return SizedBox(
+      width: 36,
+      height: 36,
+      child: IconButton(
+        tooltip: tooltip,
+        onPressed: onPressed,
+        padding: EdgeInsets.zero,
+        style: IconButton.styleFrom(
+          backgroundColor: const Color(0x80000000),
+          foregroundColor: Colors.white,
+          shape: const CircleBorder(),
+        ),
+        icon: const Icon(Icons.fullscreen_exit_rounded, size: 18),
+      ),
+    );
+  }
+}