优化了 启动录制效果

lib/features/recording/pages/page_record.dart

@@ -298,7 +298,10 @@ class _RecordingPageState extends ConsumerState<RecordingPage> {
                       onUnlocked: () => viewModel.setTouchLocked(false),
                     ),
                   if (state.isStartingRecording)
-                    const RecordingLoadingOverlayWidget(message: '正在开始录制…'),
+                    RecordingLoadingOverlayWidget(
+                      message: '正在开始录制…',
+                      backgroundColor: Colors.black.withValues(alpha: 0.24),
+                    ),
                 ],
               ),
             ),

lib/features/recording/widgets/widget_recording_button.dart

@@ -46,8 +46,8 @@ class RecordingControlButton extends StatelessWidget {
               ),
             ),
             AnimatedContainer(
-              duration: const Duration(milliseconds: 300),
-              curve: Curves.easeInOutCubic,
+              duration: const Duration(milliseconds: 500),
+              curve: Curves.ease,
               width: innerSize,
               height: innerSize,
               decoration: BoxDecoration(

lib/features/recording/widgets/widget_recording_loading_overlay.dart

@@ -3,15 +3,20 @@ import 'package:flutter_screenutil/flutter_screenutil.dart';
 
 /// 录制加载遮罩（相机启动/开始录制）
 class RecordingLoadingOverlayWidget extends StatelessWidget {
-  const RecordingLoadingOverlayWidget({super.key, required this.message});
+  const RecordingLoadingOverlayWidget({
+    super.key,
+    required this.message,
+    this.backgroundColor = Colors.black,
+  });
 
   final String message;
+  final Color backgroundColor;
 
   @override
   /// 显示加载动画与提示文案
   Widget build(BuildContext context) {
     return ColoredBox(
-      color: Colors.black,
+      color: backgroundColor,
       child: Center(
         child: Column(
           mainAxisSize: MainAxisSize.min,