feat: 完善 Web 界面国际化支持

- 将包含数字的无意义 i18n 键名替换为语义化名称 (如 kvm_text1 → about_title)
- 为缺失多语言支持的界面文本添加中英文翻译
- 修复不准确的翻译内容和 HTML 标签格式错误
- 更新所有 Pug 模板文件以使用新的 i18n 键名
- 新增登录页面"记住我"、USB 连接确认等功能的多语言支持
- 统一翻译键命名规范，提升代码可维护性

web/vnc/index.pug

@@ -9,13 +9,13 @@ append vars
 		index_link = true
 
 block start
-	p.text(i18n="vnc_text1")
+	p.text(i18n="vnc_daemon_running")
 		| This PiKVM device has running #[b kvmd-vnc] daemon and provides VNC access to the server.
-	p.text(i18n="vnc_text2")
+	p.text(i18n="vnc_security_warning")
 		| #[b WARNING!] We strongly don't recommend you to use VNC in untrusted networks without
 		| enabled X.509 or TLS encryption. Otherwise your passwords are transmitted in a plain text
 		| over the network.
-	p.text(i18n="vnc_text3")
+	p.text(i18n="vnc_client_requirements")
 		| Your VNC client must support Tight JPEG compression and password authentication.
 		| #[a(href="https://tigervnc.org") TigerVNC] is a good choice.
 		| On Linux, this client will most likely be available for installation from the repository.