Add zh/en i18n and follow DSH locale.bind for UI.

Wire API/delivery/tool strings through lib/i18n.js, and make the sidebar use ctx.locale.bind plus locale/change so English host preference no longer stays frozen on Chinese.

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

test/i18n.test.js

@@ -0,0 +1,62 @@
+import { describe, it } from 'node:test'
+import assert from 'node:assert/strict'
+import {
+  MESSAGES,
+  apiError,
+  formatRunResultBody,
+  normalizeLocale,
+  resolveLocale,
+  t,
+  workspaceTitleFromCronFork,
+} from '../lib/index.js'
+
+describe('dsh-ops-cron i18n', () => {
+  it('normalizes locales', () => {
+    assert.equal(normalizeLocale('en-US'), 'en')
+    assert.equal(normalizeLocale('zh-CN'), 'zh')
+    assert.equal(normalizeLocale(''), 'zh')
+  })
+
+  it('translates API and delivery keys', () => {
+    assert.equal(t('err.login_required', 'zh'), '登录后才能使用定时任务')
+    assert.equal(t('err.login_required', 'en'), 'Sign in to use scheduled tasks')
+    assert.equal(t('tool.create', 'en'), 'Create scheduled task')
+  })
+
+  it('interpolates delivery vars', () => {
+    assert.match(t('delivery.header', 'zh', { name: '晨报' }), /晨报/)
+    assert.match(t('delivery.header', 'en', { name: 'Daily' }), /Daily/)
+  })
+
+  it('returns stable API error codes with localized message', () => {
+    const zh = apiError('login_required', 'zh')
+    const en = apiError('login_required', 'en')
+    assert.equal(zh.error, 'login_required')
+    assert.equal(en.error, 'login_required')
+    assert.equal(zh.ok, false)
+    assert.equal(zh.message, '登录后才能使用定时任务')
+    assert.equal(en.message, 'Sign in to use scheduled tasks')
+  })
+
+  it('resolves locale from Accept-Language', () => {
+    assert.equal(resolveLocale({ headers: { 'accept-language': 'en-US,en;q=0.9' } }), 'en')
+    assert.equal(resolveLocale({ headers: { 'accept-language': 'zh-CN' } }), 'zh')
+  })
+
+  it('formatRunResultBody respects locale', () => {
+    const zh = formatRunResultBody({ name: '晨报' }, 'ok', 'zh')
+    const en = formatRunResultBody({ name: 'Daily' }, 'ok', 'en')
+    assert.match(zh, /^【定时任务 · 晨报】\n/)
+    assert.match(en, /^\[Scheduled tasks · Daily\]\n/)
+  })
+
+  it('strips English title prefix on fork promote', () => {
+    assert.equal(workspaceTitleFromCronFork('Scheduled tasks · Daily (1)'), 'Daily (1)')
+  })
+
+  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)
+  })
+})