feat: 新增 JSONL 存储格式支持，默认存储格式改为 jsonl

JSONL（JSON Lines）每行一个 JSON 对象，采用 append 模式写入，
无需读取已有数据，大数据量下性能远优于 JSON 格式。

- 新增 AsyncFileWriter.write_to_jsonl() 核心方法
- 7 个平台新增 JsonlStoreImplement 类并注册到工厂
- 配置默认值从 json 改为 jsonl，CLI/API 枚举同步更新
- db_session.py 守卫条件加入 jsonl，避免误触 ValueError
- 词云生成支持读取 JSONL 文件，优先 jsonl 回退 json
- 原有 json 选项完全保留，向后兼容
- 更新相关文档和测试

store/kuaishou/__init__.py

@@ -36,6 +36,7 @@ class KuaishouStoreFactory:
         "db": KuaishouDbStoreImplement,
         "postgres": KuaishouDbStoreImplement,
         "json": KuaishouJsonStoreImplement,
+        "jsonl": KuaishouJsonlStoreImplement,
         "sqlite": KuaishouSqliteStoreImplement,
         "mongodb": KuaishouMongoStoreImplement,
         "excel": KuaishouExcelStoreImplement,

store/kuaishou/_store_impl.py

@@ -167,6 +167,21 @@ class KuaishouJsonStoreImplement(AbstractStore):
         pass
 
 
+class KuaishouJsonlStoreImplement(AbstractStore):
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self.writer = AsyncFileWriter(platform="kuaishou", crawler_type=crawler_type_var.get())
+
+    async def store_content(self, content_item: Dict):
+        await self.writer.write_to_jsonl(item_type="contents", item=content_item)
+
+    async def store_comment(self, comment_item: Dict):
+        await self.writer.write_to_jsonl(item_type="comments", item=comment_item)
+
+    async def store_creator(self, creator: Dict):
+        pass
+
+
 class KuaishouSqliteStoreImplement(KuaishouDbStoreImplement):
     async def store_creator(self, creator: Dict):
         pass