feat(api+app): 对话阶段化、回忆录流水线与客户端会话体验

- DB: segments 用户输入文本（Alembic 0002）
- Chat: 阶段检测/阶段提示/回复限制，编排与访谈/画像 prompts 调整
- Memoir: 忠实度检查 agent，叙事与分类等链路更新
- Core: agent 日志、Alembic 启动、LangChain/日志/配置等
- Story: time_hints；Memory 检索与相关测试
- Expo: 助手头像、会话页与消息拆分、实时会话与文案/i18n
- Docs/scripts/tests: 迁移脚本、LLM JSON/记忆检索文档、新增单测

api/app/adapters/storage/tencent_cos.py

@@ -51,4 +51,4 @@ class TencentCosStorage:
         try:
             self._client.delete_object(Bucket=self._bucket, Key=key)
         except (CosClientError, CosServiceError) as e:
-            logger.warning("COS delete failed: key=%s, error=%s", key, e)
+            logger.warning("COS delete failed: key={}, error={}", key, e)