重构代码，统一config配置

backend/requirements.txt

@@ -0,0 +1,46 @@
+# Core
+pydantic==2.12.5
+python-dotenv==1.2.2
+typing-extensions==4.15.0
+
+# LangChain
+langchain==1.2.15
+langchain-community==0.4.1
+langchain-core==1.2.28
+langchain-openai==1.1.12
+langchain-qdrant==1.1.0
+langgraph==1.1.6
+langgraph-checkpoint-postgres==3.0.5
+tiktoken>=0.12.0
+
+# Vector DB
+qdrant-client==1.17.1
+
+# Memory
+mem0ai==1.0.11
+
+# Backend
+fastapi==0.135.3
+uvicorn[standard]==0.44.0
+
+# Database
+asyncpg==0.31.0
+psycopg[binary]==3.3.3
+
+# HTTP
+httpx==0.28.1
+aiohttp==3.13.5
+
+# Utilities
+tenacity==9.1.4
+rich==15.0.0
+PyYAML==6.0.3
+numpy>=1.26.2
+
+# Document Processing
+unstructured==0.22.21
+pypdf==6.10.0
+beautifulsoup4==4.14.3
+lxml==6.1.0
+pandas==3.0.2        # 若需Excel保留，否则移除
+spacy==3.8.14         # unstructured 可能依赖