重构文档目录和仓库服务，添加可选的Readme字段，更新相关数据库迁移，优化目录扫描和README生成逻辑，改进搜索功能以支持关键字过滤。

Author: 239573049

KoalaWiki.Domains/DocumentCatalog.cs

@@ -1,7 +1,4 @@
-using System.ComponentModel.DataAnnotations.Schema;
-using KoalaWiki.Domains;
-
-namespace KoalaWiki.Entities;
+namespace KoalaWiki.Domains;
 
 public class DocumentCatalog : Entity<string>
 {

KoalaWiki.Domains/Warehouse.cs

@@ -44,12 +44,12 @@ public class Warehouse : Entity<string>
     /// <summary>
     /// 仓库类型
     /// </summary>
-    public string Type { get; set; }
+    public string? Type { get; set; }
 
     /// <summary>
     /// 仓库分支
     /// </summary>
-    public string Branch { get; set; }
+    public string? Branch { get; set; }
 
     /// <summary>
     /// 仓库状态
@@ -59,17 +59,17 @@ public class Warehouse : Entity<string>
     /// <summary>
     /// 错误信息
     /// </summary>
-    public string Error { get; set; }
+    public string? Error { get; set; }
 
     /// <summary>
     /// 构建提示词
     /// </summary>
-    public string Prompt { get; set; }
+    public string? Prompt { get; set; }
 
     /// <summary>
     /// 仓库版本
     /// </summary>
-    public string Version { get; set; }
+    public string? Version { get; set; }
 
     /// <summary>
     /// 是否嵌入完成
@@ -86,5 +86,10 @@ public class Warehouse : Entity<string>
     /// 优化过的代码目录结构
     /// </summary>
     /// <returns></returns>
-    public string OptimizedDirectoryStructure { get; set; }
+    public string? OptimizedDirectoryStructure { get; set; }
+    
+    /// <summary>
+    /// 当前仓库的文档（默认使用仓库，如果没有则动态生成）
+    /// </summary>
+    public string? Readme { get; set; } 
 }