feat(admin): migrate admin UI to Vue3

admin-frontend/src/api/admin.js

@@ -0,0 +1,17 @@
+import { api } from './client'
+
+export async function updateAdminUsername(newUsername) {
+  const { data } = await api.put('/admin/username', { new_username: newUsername })
+  return data
+}
+
+export async function updateAdminPassword(newPassword) {
+  const { data } = await api.put('/admin/password', { new_password: newPassword })
+  return data
+}
+
+export async function logout() {
+  const { data } = await api.post('/logout')
+  return data
+}
+