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

test/components/connection/forwardRules.test.ts

@@ -11,6 +11,7 @@ import {
 describe('forward rule persistence', () => {
   it('uses stable session ids instead of runtime connection ids', () => {
     expect(portForwardStorageKey('saved-1', 'tab-1')).toBe('portForwards_session_saved-1')
+    expect(portForwardStorageKey(undefined, 'tab-1', 'conn-9')).toBe('portForwards_conn_conn-9')
     expect(portForwardStorageKey(undefined, 'tab-1')).toBe('portForwards_tab_tab-1')
   })