实现Area标题栏拖动时显示停靠指示器功能

- 在Area.vue中添加areaDragStart、areaDragMove、areaDragEnd事件发射
- 在DockLayout.vue中添加相应的拖拽事件处理函数
- 拖动Area标题栏时现在会显示停靠指示器，类似于Tab拖动的行为
- 符合用户需求：Area内容区可以嵌套放置Area时需要显示停靠指示器

AutoRobot/Windows/Robot/Web/src/DockLayout/Area.vue

@@ -215,7 +215,7 @@ const areaStyle = computed(() => {
   return style
 })
 
-const emit = defineEmits(['close', 'update:WindowState', 'update:position', 'dragover', 'dragleave'])
+const emit = defineEmits(['close', 'update:WindowState', 'update:position', 'dragover', 'dragleave', 'areaDragStart', 'areaDragMove', 'areaDragEnd'])
 
 // 处理Panel的最大化事件
 const onPanelMaximize = (panelId) => {
@@ -254,6 +254,15 @@ const onDragStart = (e) => {
     y: originalPosition.value.top || 0
   }
   
+  // 通知父组件拖拽开始
+  emit('areaDragStart', {
+    areaId: props.id,
+    clientX: e.clientX,
+    clientY: e.clientY,
+    startLeft: originalPosition.value.left || 0,
+    startTop: originalPosition.value.top || 0
+  })
+  
   // 添加全局事件监听
   document.addEventListener('mousemove', onDragMove)
   document.addEventListener('mouseup', onDragEnd)
@@ -289,12 +298,28 @@ const onDragMove = (e) => {
   originalPosition.value.left = newLeft
   originalPosition.value.top = newTop
   
+  // 通知父组件拖拽移动
+  emit('areaDragMove', {
+    areaId: props.id,
+    clientX: e.clientX,
+    clientY: e.clientY,
+    left: newLeft,
+    top: newTop
+  })
+  
   // 通知父组件位置变化
   emit('update:position', { left: newLeft, top: newTop })
 }
 
 // 拖拽结束
 const onDragEnd = () => {
+  // 通知父组件拖拽结束
+  emit('areaDragEnd', {
+    areaId: props.id,
+    left: originalPosition.value.left,
+    top: originalPosition.value.top
+  })
+  
   isDragging.value = false
   // 移除全局事件监听
   document.removeEventListener('mousemove', onDragMove)