fix: resolve tenant user assignment bug (#490)

- Fix frontend payload mapping (tenantSlug -> companyCode) in adminApi.ts.
- Fix backend group member fetching to avoid dummy members in UserGroupService.List.
- Fix backend foreign key violation on group creation by distinguishing between tenant parent and group parent in UserGroupService.Create.

adminfront/src/lib/adminApi.ts

@@ -445,9 +445,15 @@ export async function fetchUser(userId: string) {
 }
 
 export async function createUser(payload: UserCreateRequest) {
+  // Map tenantSlug to companyCode for backend compatibility
+  const requestPayload: any = { ...payload };
+  if (payload.tenantSlug !== undefined) {
+    requestPayload.companyCode = payload.tenantSlug;
+  }
+  
   const { data } = await apiClient.post<UserCreateResponse>(
     "/v1/admin/users",
-    payload,
+    requestPayload,
   );
   return data;
 }
@@ -466,9 +472,16 @@ export function exportUsersCSVUrl(search?: string, tenantSlug?: string) {
 }
 
 export async function bulkCreateUsers(users: BulkUserItem[]) {
+  const mappedUsers = users.map((u) => {
+    const mapped: any = { ...u };
+    if (u.tenantSlug !== undefined) {
+      mapped.companyCode = u.tenantSlug;
+    }
+    return mapped;
+  });
   const { data } = await apiClient.post<BulkUserResponse>(
     "/v1/admin/users/bulk",
-    { users },
+    { users: mappedUsers },
   );
   return data;
 }
@@ -480,7 +493,11 @@ export async function bulkUpdateUsers(payload: {
   tenantSlug?: string;
   department?: string;
 }) {
-  const { data } = await apiClient.put("/v1/admin/users/bulk", payload);
+  const requestPayload: any = { ...payload };
+  if (payload.tenantSlug !== undefined) {
+    requestPayload.companyCode = payload.tenantSlug;
+  }
+  const { data } = await apiClient.put("/v1/admin/users/bulk", requestPayload);
   return data;
 }
 
@@ -492,9 +509,14 @@ export async function bulkDeleteUsers(userIds: string[]) {
 }
 
 export async function updateUser(userId: string, payload: UserUpdateRequest) {
+  const requestPayload: any = { ...payload };
+  if (payload.tenantSlug !== undefined) {
+    requestPayload.companyCode = payload.tenantSlug;
+  }
+
   const { data } = await apiClient.put<UserSummary>(
     `/v1/admin/users/${userId}`,
-    payload,
+    requestPayload,
   );
   return data;
 }