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/src/services/license.rs

@@ -86,8 +86,8 @@ pub fn get_or_create_device_id(app: &AppHandle) -> Result<String, String> {
 }
 
 fn sign_payload(payload_b64: &str, secret: &str) -> Result<String, String> {
-    let mut mac =
-        HmacSha256::new_from_slice(secret.as_bytes()).map_err(|error| format!("HMAC 初始化失败: {error}"))?;
+    let mut mac = HmacSha256::new_from_slice(secret.as_bytes())
+        .map_err(|error| format!("HMAC 初始化失败: {error}"))?;
     mac.update(payload_b64.as_bytes());
     Ok(URL_SAFE_NO_PAD.encode(mac.finalize().into_bytes()))
 }