feat: add admin UI for reviewing pending student registrations.

Let staff list, inspect, approve, or reject enrollment and class-request submissions before final enrollment.

src/api/pendingStudentApi.js

@@ -0,0 +1,8 @@
+import axiosInstance from './axiosInstance';
+
+export const pendingStudentApi = {
+  getAll: (params) => axiosInstance.get('/pending-students/admin/get-all', { params }),
+  getOne: (id) => axiosInstance.get(`/pending-students/admin/get-one/${id}`),
+  approve: (id, data = {}) => axiosInstance.post(`/pending-students/admin/${id}/approve`, data),
+  reject: (id, data = {}) => axiosInstance.post(`/pending-students/admin/${id}/reject`, data)
+};