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/index.html

@@ -81,17 +81,17 @@
         </div>
         <div id="app-keyboard-warning">
           <hr>
-          <p class="text" i18n="index_text_1">
+          <p class="text" i18n="keyboard_limitation_note">
             Please note that when you are working with a KVM session or another application that captures the keyboard,
             you can't use some keyboard shortcuts such as Ctrl+Alt+Del (which will be caught by your OS) or Ctrl+W (caught by your browser).
           </p>
-          <p class="text" i18n="index_text_2">To override this limitation you can use <a target="_blank" href="https://google.com/chrome">Google Chrome</a>
+          <p class="text" i18n="browser_solution_note">To override this limitation you can use <a target="_blank" href="https://google.com/chrome">Google Chrome</a>
             or <a target="_blank" href="https://chromium.org/Home">Chromium</a> in application mode.
           </p>
-          <div class="code" id="app-text"></div>
+          <div class="code hidden" id="app-text"></div>
         </div>
         <hr>
-        <p class="text credits"><a target="_blank" href="https://github.com/mofeng-git/One-KVM" i18n="index_text_12">One-KVM Project</a>&nbsp; | &nbsp;<a target="_blank" href="https://one-kvm.mofeng.run" i18n="index_text_13">One-KVM Documentation</a></p>
+        <p class="text credits"><a target="_blank" href="https://github.com/mofeng-git/One-KVM" i18n="onekvm_project_link">One-KVM Project</a>&nbsp; | &nbsp;<a target="_blank" href="https://one-kvm.mofeng.run" i18n="onekvm_documentation_link">One-KVM Documentation</a></p>
       </div>
     </div>
   </body>