refactor: 设置默认Builder配置函数和Application配置函数

新增修改BlogEssay工具函数

YaeBlog.Core/Models/BlogEssay.cs

@@ -16,6 +16,22 @@ public class BlogEssay
 
     public required string HtmlContent { get; init; }
 
+    public BlogEssay WithNewHtmlContent(string newHtmlContent)
+    {
+        var essay = new BlogEssay
+        {
+            Title = Title,
+            FileName = FileName,
+            PublishTime = PublishTime,
+            Description = Description,
+            WordCount = WordCount,
+            HtmlContent = newHtmlContent
+        };
+        essay.Tags.AddRange(Tags);
+
+        return essay;
+    }
+
     public override string ToString()
     {
         return $"{Title}-{PublishTime}";