Add uds-auth zh/en i18n, UAC-branded settings, and QR expire/fail overlay.

Wire client locale to the DSH host, return stable API error codes with localized messages, and replace bottom refresh with an in-frame retry for expired or offline QR.

Co-authored-by: Cursor <cursoragent@cursor.com>

uds-auth/test/i18n.test.js

@@ -0,0 +1,53 @@
+import { describe, it } from 'node:test'
+import assert from 'node:assert/strict'
+import {
+  t,
+  normalizeLocale,
+  apiError,
+  apiOk,
+  roleLabel,
+  roleBadge,
+  MESSAGES,
+} from '../lib/i18n.js'
+
+describe('uds-auth i18n', () => {
+  it('normalizes locales', () => {
+    assert.equal(normalizeLocale('en-US'), 'en')
+    assert.equal(normalizeLocale('zh-CN'), 'zh')
+    assert.equal(normalizeLocale(''), 'zh')
+  })
+
+  it('translates UI keys', () => {
+    assert.equal(t('ui.logout', 'zh'), '退出登录')
+    assert.equal(t('ui.logout', 'en'), 'Sign out')
+  })
+
+  it('interpolates vars', () => {
+    assert.equal(t('ui.pager', 'en', { total: 3, page: 1, totalPages: 2 }), '3 users, page 1 / 2')
+  })
+
+  it('returns stable API error codes with localized message', () => {
+    const zh = apiError('not_logged_in', 'zh')
+    const en = apiError('not_logged_in', 'en')
+    assert.equal(zh.error, 'not_logged_in')
+    assert.equal(en.error, 'not_logged_in')
+    assert.equal(zh.message, '未登录')
+    assert.equal(en.message, 'Not signed in')
+  })
+
+  it('returns localized success messages', () => {
+    assert.equal(apiOk('config_saved', 'en').message, 'Config saved')
+  })
+
+  it('role labels are consistent', () => {
+    assert.equal(roleLabel('super_admin', 'zh'), '超级管理员')
+    assert.equal(roleBadge('super_admin', 'zh'), '超管')
+    assert.equal(roleLabel('super_admin', 'en'), 'Super admin')
+  })
+
+  it('zh and en tables share the same keys', () => {
+    const zhKeys = Object.keys(MESSAGES.zh).sort()
+    const enKeys = Object.keys(MESSAGES.en).sort()
+    assert.deepEqual(zhKeys, enKeys)
+  })
+})