feat: 添加员工同步立即执行按钮

在系统设置页面的员工同步配置中增加"立即同步"按钮，
允许管理员手动触发钉钉员工数据同步

frontend/src/views/admin/system-settings.vue

@@ -140,6 +140,14 @@
                 <el-button @click="testSyncConnection" :loading="syncTesting" :disabled="!syncForm.configured">
                   测试连接
                 </el-button>
+                <el-button 
+                  type="success" 
+                  @click="triggerSync" 
+                  :loading="syncing" 
+                  :disabled="!syncForm.configured"
+                >
+                  立即同步
+                </el-button>
               </el-form-item>
             </el-form>
           </div>
@@ -164,6 +172,7 @@ const dingtalkFormRef = ref<FormInstance>()
 const syncLoading = ref(false)
 const syncSaving = ref(false)
 const syncTesting = ref(false)
+const syncing = ref(false)
 const syncFormRef = ref<FormInstance>()
 
 // 钉钉配置表单
@@ -327,6 +336,31 @@ const testSyncConnection = async () => {
   }
 }
 
+/**
+ * 立即执行员工同步
+ */
+const triggerSync = async () => {
+  syncing.value = true
+  try {
+    const response = await request.post('/api/v1/employee-sync/sync')
+    if (response.success) {
+      const data = response.data
+      ElMessage.success(
+        `同步完成！共处理 ${data.total_employees || 0} 名员工，` +
+        `创建 ${data.users_created || 0} 个账号，` +
+        `跳过 ${data.users_skipped || 0} 个`
+      )
+    } else {
+      ElMessage.error(response.message || '同步失败')
+    }
+  } catch (error: any) {
+    console.error('员工同步失败:', error)
+    ElMessage.error(error?.response?.data?.detail || '员工同步失败')
+  } finally {
+    syncing.value = false
+  }
+}
+
 // 页面加载时获取配置
 onMounted(() => {
   loadDingtalkConfig()