修复注册流程不写入持久化登录态、注册失败500错误显示原始英文

Register组件缺少Login同款的keep-logged-in挂载副作用，导致注册产生的
新账号在下一次刷新时静默丢失会话（无报错、无跳转登录页）。
另外注册走原生WS {acc}协议而非REST，未接入CTRL_ERROR_TEXT_CN翻译表，
"internal error (500)"等错误会原样展示给用户。

第十轮最小粒度测试 Ch1-2 发现。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/views/tinode-web.jsx

@@ -177,7 +177,8 @@ const CTRL_ERROR_TEXT_CN = {
   'authentication required': '请先登录',
   'unknown authentication scheme': '登录方式不受支持，请刷新页面重试',
   'policy violation': '当前操作不符合安全策略要求',
-  'permission denied': '没有权限执行此操作，请重新登录'
+  'permission denied': '没有权限执行此操作，请重新登录',
+  'internal error': '服务器繁忙，请稍后重试'
 };
 function translateCtrlError(err) {
   const raw = err && err.message;
@@ -1517,7 +1518,15 @@ class TinodeWeb extends React.Component {
           this.handleLoginSuccessful(this);
         }
       }).catch(err => {
-        this.handleError(err.message, 'err');
+        // Registration goes over the native WS {acc} protocol, not REST, so im-api.js's
+        // REASON_MESSAGES translation table (REST-only) never sees this error -- it was showing
+        // raw SDK text like "internal error (500)" verbatim (confirmed live: retrying a phone
+        // number that's already registered). CTRL_ERROR_TEXT_CN already translates this same class
+        // of {ctrl} error for login; reused here with a registration-appropriate fallback instead
+        // of loginErrorMessage's own (its 401/403 fallback is "账号或密码错误", which doesn't fit a
+        // failed registration).
+        const known = translateCtrlError(err);
+        this.handleError(known || (err && err.message) || '注册失败，请稍后重试', 'err');
       });
   }