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

package.json

@@ -1,7 +1,7 @@
 {
   "name": "opsxshell-gui",
   "version": "2.1.1",
-  "description": "轻量原生的跨平台 SSH/SFTP 运维终端 · Tauri 2 + Rust",
+  "description": "轻量原生的跨平台运维终端 · SSH / SFTP / 转发 / RDP·VNC · Tauri 2 + Rust",
   "author": "OpsXShell Team",
   "license": "MIT",
   "scripts": {
@@ -46,6 +46,7 @@
     "@xterm/addon-web-links": "^0.11.0",
     "@xterm/xterm": "^5.5.0",
     "husky": "^9.1.7",
+    "i18next": "^26.3.6",
     "lint-staged": "^16.4.0",
     "lucide-react": "^0.294.0",
     "monaco-editor": "^0.55.1",
@@ -53,7 +54,10 @@
     "prettier-plugin-tailwindcss": "^0.7.2",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
+    "react-i18next": "^17.0.11",
+    "react-markdown": "^10.1.0",
     "react-router-dom": "^6.21.0",
+    "remark-gfm": "^4.0.1",
     "rimraf": "^6.1.3",
     "zmodem-ts": "^1.0.8",
     "zustand": "^4.4.7"