feat: 资产解析接口新增实名时间字段

- AssetResolveResponse 新增 real_name_at 字段：card 类型取 first_realname_at，device 类型取绑定卡中最小的实名时间
- BoundCardInfo 新增 real_name_at 字段：各卡自己的 first_realname_at
- RefreshCardDataFromGateway 手动刷新路径补写实名时间：检测到 0→1 变化时同步写入 first_realname_at
- 同步更新 asset-resolve 规格文档

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/service/asset/service.go

@@ -191,10 +191,24 @@ func (s *Service) buildDeviceResolveResponse(ctx context.Context, device *model.
 				MSISDN:         c.MSISDN,
 				NetworkStatus:  c.NetworkStatus,
 				RealNameStatus: c.RealNameStatus,
+				RealNameAt:     c.FirstRealnameAt,
 				SlotPosition:   slotMap[c.ID],
 				IsCurrent:      isCurrentMap[c.ID],
 			})
 		}
+
+		// 聚合设备级 RealNameAt：取所有绑定卡 FirstRealnameAt 中的最小值（跳过 nil）
+		var minRealNameAt *time.Time
+		for _, c := range cards {
+			if c.FirstRealnameAt == nil {
+				continue
+			}
+			if minRealNameAt == nil || c.FirstRealnameAt.Before(*minRealNameAt) {
+				t := *c.FirstRealnameAt
+				minRealNameAt = &t
+			}
+		}
+		resp.RealNameAt = minRealNameAt
 	}
 
 	// 查当前主套餐
@@ -228,6 +242,7 @@ func (s *Service) buildCardResolveResponse(ctx context.Context, card *model.IotC
 		CreatedAt:           card.CreatedAt,
 		UpdatedAt:           card.UpdatedAt,
 		RealNameStatus:      card.RealNameStatus,
+		RealNameAt:          card.FirstRealnameAt,
 		NetworkStatus:       card.NetworkStatus,
 		ICCID:               card.ICCID,
 		CarrierID:           card.CarrierID,