Add user management page and technician picker for reassign

- New /admin/users page (admin only) for creating technicians,
  editing role/email, resetting passwords, deleting users
- AftersalesDetail reassign modal now uses a searchable Select
  populated from /api/users/assignable instead of raw user ID input
- Menu entry only shown to admins

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/services/api.ts

@@ -10,6 +10,10 @@ import type {
   CreateAftersalesRequest,
   UpdateAftersalesRequest,
   CustomerConfirmRequest,
+  CreateUserRequest,
+  UpdateUserRequest,
+  UserListFilter,
+  UserListResponse,
 } from '@/types';
 
 const API_BASE_URL = import.meta.env.VITE_API_BASE_URL || '/api';
@@ -433,4 +437,55 @@ export const aftersalesApi = {
     }
     throw new Error(response.data.error || '提交确认失败');
   },
+};
+
+export const usersApi = {
+  list: async (filter?: UserListFilter) => {
+    const params = new URLSearchParams();
+    if (filter?.page && filter.page > 1) params.append('page', String(filter.page));
+    if (filter?.limit && filter.limit !== 20) params.append('limit', String(filter.limit));
+    if (filter?.role) params.append('role', filter.role);
+    if (filter?.search) params.append('search', filter.search);
+
+    const url = params.toString() ? `/users?${params.toString()}` : '/users';
+    const response = await apiClient.get(url);
+    return response.data as UserListResponse;
+  },
+
+  create: async (data: CreateUserRequest) => {
+    const response = await apiClient.post('/users', data);
+    if (response.data.user) {
+      return response.data.user as User;
+    }
+    throw new Error(response.data.error || '创建用户失败');
+  },
+
+  update: async (id: number, data: UpdateUserRequest) => {
+    const response = await apiClient.patch(`/users/${id}`, data);
+    if (response.data.user) {
+      return response.data.user as User;
+    }
+    throw new Error(response.data.error || '更新用户失败');
+  },
+
+  resetPassword: async (id: number, newPassword: string) => {
+    const response = await apiClient.post(`/users/${id}/reset-password`, { newPassword });
+    if (response.data.message) {
+      return true;
+    }
+    throw new Error(response.data.error || '重置密码失败');
+  },
+
+  delete: async (id: number) => {
+    const response = await apiClient.delete(`/users/${id}`);
+    if (response.data.message) {
+      return true;
+    }
+    throw new Error(response.data.error || '删除用户失败');
+  },
+
+  assignable: async () => {
+    const response = await apiClient.get('/users/assignable');
+    return (response.data?.data || []) as User[];
+  },
 };