feat(theme): 提供i18n能力

theme-terminal/templates/modules/layout.html

@@ -1,11 +1,14 @@
 <!DOCTYPE html>
-<html lang="en" th:fragment="html (header, content, footer)">
+<html
+  xmlns:th="https://www.thymeleaf.org"
+  th:lang="${#locale.toLanguageTag}" 
+  th:fragment="html (header, content, footer)">
   <head>
     <meta charset="UTF-8" />
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <link rel="icon" type="image/x-icon" th:href="${theme.config.basic.favicon}">
-    <title th:text="${site.title}"></title>
+    <title th:text="${title}"></title>
     <link rel="manifest" th:href="@{/assets/dist/manifest.json}" />
     <link rel="stylesheet" th:href="@{/assets/dist/main.css?version={version}(version=${theme.spec.version})}" href="./assets/dist/style.css" />
   </head>