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/utils/terminalPanes.test.ts

@@ -27,10 +27,10 @@ describe('terminal pane input routing', () => {
     expect(resolveTerminalInputTargets(panes, 'missing', false)).toEqual([])
   })
 
-  it('never broadcasts input originating from a local terminal', () => {
-    expect(shouldBroadcastTerminalInput(true, true, 'local')).toBe(false)
-    expect(shouldBroadcastTerminalInput(true, true, 'ssh-connection')).toBe(false)
+  it('broadcasts from both SSH and local terminals when enabled', () => {
+    expect(shouldBroadcastTerminalInput(true, true, 'local')).toBe(true)
     expect(shouldBroadcastTerminalInput(true, false, 'ssh-connection')).toBe(true)
     expect(shouldBroadcastTerminalInput(true, false, null)).toBe(false)
+    expect(shouldBroadcastTerminalInput(false, false, 'ssh-connection')).toBe(false)
   })
 })