feat: 商户冻结/解冻功能及字典缓存重构

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/Domain/TakeoutSaaS.Domain/Identity/Entities/IdentityUser.cs

@@ -79,7 +79,7 @@ public sealed class IdentityUser : AuditableEntityBase
     public string? Avatar { get; set; }
 
     /// <summary>
-    /// 并发控制字段。
+    /// 并发控制字段（映射到 PostgreSQL xmin）。
     /// </summary>
-    public byte[] RowVersion { get; set; } = Array.Empty<byte>();
+    public uint RowVersion { get; set; }
 }