refactor(ScanQRcode): 优化纹理原始数据获取逻辑

将直接获取的原始数据缓存后再转为数组，避免重复调用获取开销

Assets/Scripts/UI/Pages/ConnectDevice/ScanQRcode.cs

@@ -383,7 +383,8 @@ namespace Kill.UI.Pages
                     if (useAsyncScan)
                     {
                         // 直接获取 RGB24 原始字节，无需手动转换
-                        byte[] rgbBytes = previewTexture.GetRawTextureData<byte>();
+                        var rawData = previewTexture.GetRawTextureData<byte>();
+                        byte[] rgbBytes = rawData.ToArray();
                         int texWidth = previewTexture.width;
                         int texHeight = previewTexture.height;