添加用户权限查询功能，解码JWT以获取用户ID，并根据权限更新用户权限状态

ui/src/components/study/ProblemList.vue

@@ -11,7 +11,7 @@
           刷新
         </v-btn>
         <v-dialog v-model="dialog0" max-width="500px">
-          <template v-slot:activator="{ props }">
+          <template v-if="userPermission == '1'" v-slot:activator="{ props }">
             <v-btn class="mb-2" color="primary" dark v-bind="props">
               新建题目
             </v-btn>
@@ -124,6 +124,7 @@ import { useAuthStore } from '@/store/auth';
 import axios, { Axios, AxiosError } from 'axios';
 import { computed, nextTick, onMounted, ref, watch } from 'vue';
 import * as mathjs from 'mathjs';
+import { jwtDecode, type JwtPayload } from 'jwt-decode';
 
 const loading = ref(false);
 const refresh = async () => {
@@ -278,6 +279,45 @@ watch(dialogDelete, (val) => {
 const authStore = useAuthStore();
 const storedToken = ref(authStore.token);
 
+interface KqmJwt extends JwtPayload {
+  user_id: string;
+};
+
+const userId = computed(() => {
+  if (storedToken.value != '') {
+    let data: KqmJwt = jwtDecode(storedToken.value);
+    return data.user_id;
+  }
+  return '';
+});
+
+type UserPermissionResponse = { success?: string, permission?: string, error?: string };
+
+const queryPermission = async () => {
+  try {
+    const formData = new FormData;
+    formData.append("user_id", userId.value);
+    let res = await axios.post('/api/auth/permission', formData);
+    return res.data as UserPermissionResponse;
+  } catch (e) {
+    let ex = e as AxiosError;
+    return ex.response?.data as UserPermissionResponse;
+  }
+}
+
+const userPermission = ref('');
+
+const updateUserPermission = async () => {
+  let res = await queryPermission();
+  if (res?.success) {
+    userPermission.value = res.permission as string;
+  } else {
+    userPermission.value = '';
+  }
+}
+
+watch(userId, updateUserPermission, { immediate: true });
+
 const decorate = <T>(ex: AxiosError) => {
   if (ex.response?.data) {
     return ex.response?.data as T;