docs(03-persistence): mention SQLite as an alternative backend (#26)

* docs(03-persistence): mention SQLite as an alternative backend

* Update README with persistence options and SQLite note

Clarify persistence options and mention SQLite as a potential upgrade for handling concurrent writers and richer queries.

* Revise persistence options in README.zh.md

Updated the section on persistence options to clarify the transition from file-based storage to database solutions like SQLite and Postgres.

* Fix typos and enhance clarity in README.md

Corrected spelling of 'Postgre' to 'Postgres' and improved clarity of the note about persistence.

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Co-authored-by: Zane Chen <99708452+czl9707@users.noreply.github.com>

03-persistence/README.md

@@ -46,6 +46,9 @@ class HistoryStore:
         """Get all messages for a session."""
 ```
 
+## Note
+
+The file-based store is deliberately simple, and it's still many agents handle persistence today. The persistence would naturally grow into a database solution as the project scale up. Sqlite, Postgres, you name them. This project already have the `HistoryStore` abstraction, building a more sophisticated persistence class should not be affect other pieces in this project.
 
 ## Try it out
 

03-persistence/README.zh.md

@@ -47,6 +47,10 @@ class HistoryStore:
 ```
 
 
+## 持久化实现方式
+
+基于文件的存储刻意保持简单，许多智能体仍然这样处理持久化。如果之后你需要扩展项目，数据库是一个自然的进阶选择。Sqlite，Postgres 等等。由于一切都通过 `HistoryStore` 接口进行，实现一个更加复杂的持久化方案不会影响项目的其他部分。
+
 ## 试一试
 
 ```bash