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-tauri/tauri.conf.json

@@ -12,11 +12,13 @@
   "app": {
     "windows": [
       {
+        "label": "main",
         "title": "OpsXShell",
         "width": 1280,
         "height": 800,
-        "minWidth": 960,
-        "minHeight": 640,
+        "minWidth": 1024,
+        "minHeight": 700,
+        "resizable": true,
         "decorations": true,
         "transparent": false
       }