feat(usercenter): SSO /sso 落地页(拿票兑会话→自动登录)

App 打开 app.yanmeiai.com/sso?t=<ticket>&redirect=<路径>;本页 exchangeWebTicket→setSession
(与正常登录同路径)→跳白名单相对路径。镜像 jiu sso.njk。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nMthbVEmQquxBRKb9Fj8u

web/usercenter/lib/i18n.ts

@@ -27,6 +27,12 @@ export const STRINGS: Record<string, Entry> = {
   loginLocked: { zh: '失败次数过多,账户已临时锁定', en: 'Too many attempts — account temporarily locked' },
   lockedCountdown: { zh: '请于 {s} 秒后重试', en: 'Try again in {s}s' },
 
+  /* sso（App→网页免登录落地页） */
+  ssoTitle: { zh: '正在登录…', en: 'Signing in…' },
+  ssoMsg: { zh: '正在验证来自 App 的登录票据', en: 'Verifying the sign-in ticket from the app' },
+  ssoFailTitle: { zh: '登录跳转失败', en: 'Sign-in redirect failed' },
+  ssoFailHint: { zh: '即将跳转到登录页,请手动登录', en: 'Redirecting to the login page, please sign in manually' },
+
   /* overview */
   greeting: { zh: '欢迎回来', en: 'Welcome back' },
   curPlan: { zh: '当前套餐', en: 'Current plan' },