refactor: rename checkStartWithHttp to isHttpLink

- Update function name and implementation in utils/index.js
- Replace all occurrences in getPageProperties.js, post.js, and BlogPostCard.js
- Improve function documentation and use regex for better URL matching

lib/utils/index.js

@@ -89,19 +89,16 @@ export function isUrl(str) {
     return false
   }
 
-  return str?.indexOf('/') === 0 || checkStartWithHttp(str)
+  return str?.indexOf('/') === 0 || isHttpLink(str)
 }
 
-// 检查是否外链
-export function checkStartWithHttp(str) {
-  // 检查字符串是否包含http
-  if (str?.indexOf('http:') === 0 || str?.indexOf('https:') === 0) {
-    // 如果包含，找到http的位置
-    return true
-  } else {
-    // 不包含
-    return false
-  }
+/**
+ * 判断是否是 http(s) 开头的链接（外部网页）
+ * @param str
+ * @returns {boolean}
+ */
+export function isHttpLink(str) {
+  return typeof str === 'string' && /^https?:\/\//i.test(str)
 }
 
 /**