feat(posts): filter posts by blocked users

Add functionality to filter out posts from blocked users in post listing endpoints. Includes a new `IsBlockedBatch` method for efficient batch checking of blocked relationships and `is_blocked` field in API responses when viewing a blocked user's posts.

internal/repository/system_notification_repo.go

@@ -3,6 +3,7 @@
 import (
 	"context"
 	"strconv"
+	"time"
 
 	"with_you/internal/model"
 	"with_you/internal/pkg/cursor"
@@ -88,7 +89,7 @@ func (r *systemNotificationRepository) GetUnreadCount(receiverID string) (int64,
 
 // MarkAsRead 标记单条通知为已读
 func (r *systemNotificationRepository) MarkAsRead(id int64, receiverID string) error {
-	now := model.SystemNotification{}.UpdatedAt
+	now := time.Now()
 	return r.db.Model(&model.SystemNotification{}).
 		Where("id = ? AND receiver_id = ?", id, receiverID).
 		Updates(map[string]any{
@@ -99,7 +100,7 @@ func (r *systemNotificationRepository) MarkAsRead(id int64, receiverID string) e
 
 // MarkAllAsRead 标记用户所有通知为已读
 func (r *systemNotificationRepository) MarkAllAsRead(receiverID string) error {
-	now := model.SystemNotification{}.UpdatedAt
+	now := time.Now()
 	return r.db.Model(&model.SystemNotification{}).
 		Where("receiver_id = ? AND is_read = ?", receiverID, false).
 		Updates(map[string]any{