삭제를 alert에서 modal로 변경

frontend/lib/api/department.ts

@@ -44,7 +44,12 @@ export async function createDepartment(companyCode: string, data: DepartmentForm
     return response.data;
   } catch (error: any) {
     console.error("부서 생성 실패:", error);
-    return { success: false, error: error.message };
+    const isDuplicate = error.response?.status === 409;
+    return {
+      success: false,
+      error: error.response?.data?.message || error.message,
+      isDuplicate,
+    };
   }
 }
 
@@ -89,18 +94,39 @@ export async function getDepartmentMembers(deptCode: string) {
   }
 }
 
+/**
+ * 사용자 검색 (부서원 추가용)
+ */
+export async function searchUsers(companyCode: string, search: string) {
+  try {
+    const response = await apiClient.get<{ success: boolean; data: any[] }>(
+      `/departments/companies/${companyCode}/users/search`,
+      { params: { search } },
+    );
+    return response.data;
+  } catch (error: any) {
+    console.error("사용자 검색 실패:", error);
+    return { success: false, error: error.message };
+  }
+}
+
 /**
  * 부서원 추가
  */
 export async function addDepartmentMember(deptCode: string, userId: string) {
   try {
-    const response = await apiClient.post<{ success: boolean }>(`/departments/${deptCode}/members`, {
+    const response = await apiClient.post<{ success: boolean; message?: string }>(`/departments/${deptCode}/members`, {
       user_id: userId,
     });
     return response.data;
   } catch (error: any) {
     console.error("부서원 추가 실패:", error);
-    return { success: false, error: error.message };
+    const isDuplicate = error.response?.status === 409;
+    return {
+      success: false,
+      error: error.response?.data?.message || error.message,
+      isDuplicate,
+    };
   }
 }