修复：CI 部署环境与 ref 错配、迁移碎片化、图片意图 source_span、章节物化脏版式、会话历史与本地语音不一致

新增：TTS 上传 COS 与分片、章节 reading_segments 物化与快照、markdown 清洗、会话消息 repository、语音 store 重构与相关测试

api/app/agents/chat/helpers.py

@@ -38,6 +38,7 @@ async def save_message(
     message_type: str = "text",
     voice_session_id: str | None = None,
     timestamp: datetime | str | int | None = None,
+    audio_duration_seconds: int | None = None,
 ) -> None:
     """保存消息到 Redis"""
     await redis_service.add_message(
@@ -49,4 +50,5 @@ async def save_message(
         timestamp=timestamp.isoformat()
         if isinstance(timestamp, datetime)
         else timestamp,
+        audio_duration_seconds=audio_duration_seconds,
     )