feat(i18n): add multi-language support (ja/ko/vi/ru/zh-TW) with system auto-detection

- Extend AppLanguage to 7 locales: zh-CN, zh-TW, en, ja, ko, vi, ru
- Auto-detect system language via navigator.languages; fallback to English
- Add BCP47 locale mapping for date formatting and sorting
- Create 50 translation JSON files (5 languages × 10 namespaces, 1137 keys each)
- Update language selector with native language names
- Extend locale key parity test to cover all 7 languages (70 assertions)
- Add VNC/RDP desktop, serial terminal, AI agent, port forwarding, and SFTP features
- Add credential encryption, host metrics, session backup crypto, and zmodem bridge
- Update Rust backend: desktop services, host metrics, SSH/SFTP enhancements

src/components/pro/UpgradeWall.tsx

@@ -2,14 +2,16 @@
  * UpgradeWall — intercepts Pro features for Free users
  */
 
+import { useTranslation } from 'react-i18next'
 import { Crown, Sparkles, X } from 'lucide-react'
 import {
-  PRO_FEATURE_LABELS,
+  proFeatureLabel,
   useEntitlementStore,
   type ProFeature,
 } from '../../stores/entitlementStore'
 
 export default function UpgradeWall() {
+  const { t } = useTranslation('common')
   const wall = useEntitlementStore((s) => s.wall)
   const closeWall = useEntitlementStore((s) => s.closeWall)
   const openUpgradeTab = useEntitlementStore((s) => s.openUpgradeTab)
@@ -17,7 +19,7 @@ export default function UpgradeWall() {
   if (!wall.open) return null
 
   const feature = wall.feature as ProFeature | undefined
-  const label = feature ? PRO_FEATURE_LABELS[feature] : '专业功能'
+  const label = feature ? proFeatureLabel(feature) : t('pro.feature')
   const comingSoon = wall.comingSoon
 
   return (
@@ -36,7 +38,7 @@ export default function UpgradeWall() {
           type="button"
           onClick={closeWall}
           className="absolute right-3 top-3 rounded-lg p-1.5 text-txt-muted hover:bg-dark-700 hover:text-content-primary"
-          aria-label="关闭"
+          aria-label={t('action.close')}
         >
           <X className="h-4 w-4" />
         </button>
@@ -46,13 +48,11 @@ export default function UpgradeWall() {
             <Crown className="h-5 w-5" />
           </div>
           <h2 id="upgrade-wall-title" className="text-base font-semibold text-content-primary">
-            {comingSoon ? `${label} · 即将推出` : `解锁 ${label}`}
+            {comingSoon ? `${label}${t('pro.wallComingSoonSuffix')}` : t('pro.wallUnlock', { feature: label })}
           </h2>
           <p className="mt-1.5 text-sm leading-relaxed text-txt-muted">
             {wall.message ||
-              (comingSoon
-                ? '该能力属于 OpsXShell Pro，协议实现尚在开发中。升级后可优先体验。'
-                : '此功能属于 OpsXShell Pro。升级后即可在本机使用。')}
+              (comingSoon ? t('pro.wallMessageComingSoon') : t('pro.wallMessageDefault'))}
           </p>
         </div>
 
@@ -62,7 +62,7 @@ export default function UpgradeWall() {
             onClick={closeWall}
             className="flex-1 rounded-lg border border-dark-600 px-3 py-2.5 text-sm text-content-secondary transition-colors hover:bg-dark-700"
           >
-            稍后再说
+            {t('pro.later')}
           </button>
           <button
             type="button"
@@ -70,7 +70,7 @@ export default function UpgradeWall() {
             className="flex flex-1 items-center justify-center gap-1.5 rounded-lg bg-accent-blue px-3 py-2.5 text-sm font-medium text-white transition-colors hover:bg-blue-600"
           >
             <Sparkles className="h-3.5 w-3.5" />
-            查看 Pro
+            {t('pro.viewPro')}
           </button>
         </div>
       </div>