fix: fix dock window shadow animation issue

1. Replaced problematic windowEffect approach with direct shadowColor
control
2. Set shadow color to transparent during hideShowAnimation to avoid
visual artifacts
3. Maintain proper shadow opacity (60% black) when animation is not
running
4. Fixes the bug where window shadows would persist incorrectly after
animations

fix: 修复任务栏窗口阴影动画问题

1. 用直接的阴影颜色控制替换有问题的 windowEffect 方法
2. 在 hideShowAnimation 期间将阴影颜色设置为透明以避免视觉伪影
3. 在动画未运行时保持正确的阴影不透明度（60%黑色）
4. 修复动画后窗口阴影错误持续存在的问题

Pms: BUG-317241

Author: wjyrich

panels/dock/package/main.qml

@@ -59,9 +59,7 @@ Window {
 
     D.DWindow.enabled: true
     D.DWindow.windowRadius: 0
-    //TODO：由于windoweffect处理有BUG，导致动画结束后一致保持无阴影，无borderwidth状态。(所以未取消阴影)
-    //目前在动画结束后还存在阴影残留 
-    //D.DWindow.windowEffect: hideShowAnimation.running ? D.PlatformHandle.EffectNoShadow | D.PlatformHandle.EffectNoBorder : 0
+    D.DWindow.shadowColor: hideShowAnimation.running ? Qt.rgba(0,0,0,0) : Qt.rgba(0,0,0,255 * 0.6)
     D.DWindow.borderWidth:  hideShowAnimation.running ? 0 : 1
     D.DWindow.enableBlurWindow: Qt.platform.pluginName !== "xcb"
     D.DWindow.themeType: Panel.colorTheme