refactor: 统一接口响应格式处理

- 修改 axios 响应拦截器，统一处理包装后的响应格式：
  - code === 0: 返回 data 中的实际数据
  - code === -1: ElMessage.error 提示 message 并 reject
  - 其他情况: 兼容原始响应格式

- 更新各页面数据取值方式：
  - 分页列表: data.data → data.list
  - SystemUser.vue, SystemRole.vue, Article.vue
  - Music.vue, Hitokoto.vue, PhotoWall.vue, SourceImage.vue
  - SystemConfigAdd.vue: data.data.exists → data.exists

- Home.vue: 简化 verifyToken 响应处理
- SystemConfig.vue: 简化 save 响应处理
- SystemRole.vue/SystemUser.vue: 简化 delete 响应处理

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/views/api/Hitokoto.vue

@@ -105,7 +105,7 @@ async function loadData() {
   selectedData = []
   loading.value = false
   total.value = data.total
-  hitokotoData.value = data.data
+  hitokotoData.value = data.list
 }
 setLoadData(loadData)
 

src/views/api/Music.vue

@@ -211,7 +211,7 @@ async function loadData() {
   selectedIds = []
   loading.value = false
   total.value = data.total
-  musicData.value = data.data
+  musicData.value = data.list
 }
 setLoadData(loadData)
 

src/views/api/PhotoWall.vue

@@ -117,7 +117,7 @@ async function loadData() {
   selectedData = []
   loading.value = false
   total.value = data.total
-  photowallData.value = data.data
+  photowallData.value = data.list
 }
 setLoadData(loadData)
 

src/views/api/SourceImage.vue

@@ -112,7 +112,7 @@ async function loadData(): Promise<void> {
   selectedData = []
   loading.value = false
   total.value = data.total
-  sourceImageData.value = data.data
+  sourceImageData.value = data.list
 }
 setLoadData(loadData)