refactor(CanvasTool): 重命名addContent为addContent2以保持一致性

将函数名从addContent改为addContent2，使其与文件名index2.vue保持一致，并更新了全局对象的导出

src/views/Editor/CanvasTool/index2.vue

@@ -366,7 +366,7 @@ interface ContentItem {
   id?: string
 }
 
-const addContent = (data: ContentItem, type: number) => {
+const addContent2 = (data: ContentItem, type: number) => {
   // contentList.value.push(data)
   if (type === 2) {
     const elements = currentSlide.value?.elements || []
@@ -380,7 +380,7 @@ const addContent = (data: ContentItem, type: number) => {
   }
 }
 
-Object.assign(window, { addContent })
+Object.assign(window, { addContent2 })
 
 // 确认对话框状态
 const confirmDialogVisible = ref(false)