feat: 游玩记录支持区分原故事和AI草稿，已下架草稿显示标签

server/app/models/story.py

@@ -123,6 +123,7 @@ class StoryDraft(Base):
     is_read = Column(Boolean, default=False)  # 用户是否已查看
     published_to_center = Column(Boolean, default=False)  # 是否发布到创作中心
     draft_type = Column(String(20), default="rewrite")  # 草稿类型: rewrite/continue/create
+    is_collected = Column(Boolean, default=False)  # 用户是否收藏
     
     created_at = Column(TIMESTAMP, server_default=func.now())
     completed_at = Column(TIMESTAMP, default=None)