fix: identity 登录并发改为 xmin

移除 identity_users 对 RowVersion 列的依赖，改用 PostgreSQL xmin 作为并发令牌，修复线上登录因缺失 RowVersion 列导致的 500 错误。

src/Application/TakeoutSaaS.Application/Identity/Commands/UpdateIdentityUserCommand.cs

@@ -50,9 +50,7 @@ public sealed record UpdateIdentityUserCommand : IRequest<UserDetailDto?>
     public string[]? RoleIds { get; init; }
 
     /// <summary>
-    /// 并发控制版本。
+    /// 并发控制版本（兼容字段，当前由数据库 xmin 托管）。
     /// </summary>
-    [Required]
-    [MinLength(1)]
-    public byte[] RowVersion { get; init; } = Array.Empty<byte>();
+    public byte[]? RowVersion { get; init; }
 }

src/Application/TakeoutSaaS.Application/Identity/Handlers/UpdateIdentityUserCommandHandler.cs

@@ -87,7 +87,6 @@ public sealed class UpdateIdentityUserCommandHandler(
         user.Phone = phone;
         user.Email = email;
         user.Avatar = string.IsNullOrWhiteSpace(request.Avatar) ? null : request.Avatar.Trim();
-        user.RowVersion = request.RowVersion;
 
         // 6. 构建操作日志消息
         var operatorName = string.IsNullOrWhiteSpace(operatorProfile.DisplayName)

src/Application/TakeoutSaaS.Application/Identity/Validators/UpdateIdentityUserCommandValidator.cs

@@ -16,7 +16,6 @@ public sealed class UpdateIdentityUserCommandValidator : AbstractValidator<Updat
         RuleFor(x => x.UserId).GreaterThan(0);
         RuleFor(x => x.DisplayName).NotEmpty().MaximumLength(64);
         RuleFor(x => x.Avatar).MaximumLength(512);
-        RuleFor(x => x.RowVersion).NotEmpty();
         RuleFor(x => x.TenantId).GreaterThan(0).When(x => x.TenantId.HasValue);
         RuleForEach(x => x.RoleIds)
             .Must(value => long.TryParse(value, out _))

src/Infrastructure/TakeoutSaaS.Infrastructure/Identity/Persistence/IdentityDbContext.cs

@@ -104,10 +104,12 @@ public sealed class IdentityDbContext(
         builder.Property(x => x.LastLoginAt);
         builder.Property(x => x.MustChangePassword).IsRequired();
         builder.Property(x => x.Avatar).HasColumnType("text");
-        builder.Property(x => x.RowVersion)
-            .IsRowVersion()
-            .IsConcurrencyToken()
-            .HasColumnType("bytea");
+        builder.Ignore(x => x.RowVersion);
+        builder.Property<uint>("xmin")
+            .HasColumnName("xmin")
+            .HasColumnType("xid")
+            .ValueGeneratedOnAddOrUpdate()
+            .IsConcurrencyToken();
         builder.Property(x => x.TenantId).IsRequired();
         ConfigureAuditableEntity(builder);
         ConfigureSoftDeleteEntity(builder);