refactor(push): change created_at format from Unix milliseconds to ISO8601

internal/service/push_service.go

@@ -1,4 +1,4 @@
-package service
+package service
 
 import (
 	"context"
@@ -153,7 +153,7 @@ func (s *pushServiceImpl) pushViaWebSocket(ctx context.Context, userID string, m
 			"type":       string(message.SystemType),
 			"content":    content,
 			"extra":      map[string]any{},
-			"created_at": message.CreatedAt.UnixMilli(),
+			"created_at": message.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
 		}
 
 		// 填充额外数据
@@ -454,7 +454,7 @@ func (s *pushServiceImpl) pushSystemViaWebSocket(ctx context.Context, userID str
 		"title":      title,
 		"content":    content,
 		"data":       data,
-		"created_at": time.Now().UnixMilli(),
+		"created_at": time.Now().Format("2006-01-02T15:04:05Z07:00"),
 	}
 	s.wsHub.PublishToUser(userID, "system_notification", sysMsg)
 	return true
@@ -483,7 +483,7 @@ func (s *pushServiceImpl) pushSystemNotificationViaWebSocket(ctx context.Context
 		"title":      notification.Title,
 		"content":    notification.Content,
 		"extra":      map[string]any{},
-		"created_at": notification.CreatedAt.UnixMilli(),
+		"created_at": notification.CreatedAt.Format("2006-01-02T15:04:05Z07:00"),
 	}
 
 	// 填充额外数据