Add core database support and enhance documentation

- Introduced `MYSQL_CORE_DATABASE` in `.env.example` and `settings.py` for core database configuration.
- Added `CoreReadOnlyRepository` for read-only access to the `jinrong_core` database.
- Updated `AGENTS.md`, `README.md`, and various documentation files to reflect new agent onboarding processes and project structure.
- Revised requirements in `requirements.txt` to include `langgraph` and `langchain-core`.
- Enhanced `FLOW.md` with local bootstrap instructions for setting up the core simulation environment.
- Added new scripts for database creation and seeding for the core simulation library.
- Improved overall documentation for clarity on project architecture and memory management.
- Updated `TODO.md` to reflect current development priorities and tasks.

requirements.txt

@@ -9,9 +9,10 @@ pymysql>=1.1.1
 redis>=5.2.0
 neo4j>=5.26.0
 
-# Vector & LLM
+# Vector & LLM / Agent 编排（LangGraph）
 pymilvus>=3.0.1
-langchain>=1.3.18
+langgraph>=1.2.11
+langchain-core>=1.6.0
 langchain-openai>=1.6.0
 httpx>=0.28.0