[fix]: role bugfix.

frontend/src/views/Welcome/index.vue

@@ -160,7 +160,13 @@ watch(
   (newLang) => {
     // 语言切换后，自动选中第一个可用角色
     if (filteredRoles.value.length > 0) {
-      role.value = filteredRoles.value[0]['id'];
+      const current_role_id = settingsStore.$state.role;
+      const current_role = filteredRoles.value.find(ro => ro['id'] == current_role_id);
+      if (current_role) {
+        role.value = current_role_id;
+      } else {
+        role.value = filteredRoles.value[0]['id'];
+      }
     } else {
       role.value = "";
     }