fix: 将平台业务ID统一改为String并自动建表

- 抖音、B站、快手、微博的帖子/视频/评论ID从BigInteger改为String，
  避免PostgreSQL下字符串写入BIGINT报错及未来ID溢出风险
- B站dynamic_id改为String，修复API返回id_str被强转int导致的精度丢失
- 知乎提取器对content_id/question_id显式str()转换
- main.py启动数据库保存模式时自动建表，无需手动--init_db
- 同步更新相关老化测试

store/bilibili/_store_impl.py

@@ -128,8 +128,7 @@ class BiliDbStoreImplement(AbstractStore):
         Args:
             content_item: content item dict
         """
-        video_id = int(content_item.get("video_id"))
-        content_item["video_id"] = video_id
+        video_id = content_item.get("video_id")
         content_item["liked_count"] = int(content_item.get("liked_count", 0) or 0)
         content_item["create_time"] = int(content_item.get("create_time", 0) or 0)
 
@@ -154,9 +153,7 @@ class BiliDbStoreImplement(AbstractStore):
         Args:
             comment_item: comment item dict
         """
-        comment_id = int(comment_item.get("comment_id"))
-        comment_item["comment_id"] = comment_id
-        comment_item["video_id"] = int(comment_item.get("video_id", 0) or 0)
+        comment_id = comment_item.get("comment_id")
         comment_item["create_time"] = int(comment_item.get("create_time", 0) or 0)
         comment_item["like_count"] = str(comment_item.get("like_count", "0"))
         comment_item["sub_comment_count"] = str(comment_item.get("sub_comment_count", "0"))
@@ -191,8 +188,7 @@ class BiliDbStoreImplement(AbstractStore):
         Args:
             dynamic_item: dynamic item dict
         """
-        dynamic_id = int(dynamic_item.get("dynamic_id"))
-        dynamic_item["dynamic_id"] = dynamic_id
+        dynamic_id = dynamic_item.get("dynamic_id")
 
         async with get_session() as session:
             result = await session.execute(select(BilibiliUpDynamic).where(BilibiliUpDynamic.dynamic_id == dynamic_id))