Add deployment tuning and chat load test

ai_knowledge_base_v2/apps/backend/.env.example

@@ -5,6 +5,10 @@ API_PREFIX=/api
 
 DATABASE_URL=mysql+pymysql://ai_kb:ai_kb@127.0.0.1:3306/ai_knowledge_base_v2?charset=utf8mb4
 REDIS_URL=
+DB_POOL_SIZE=10
+DB_MAX_OVERFLOW=20
+DB_POOL_TIMEOUT=30
+DB_POOL_RECYCLE=1800
 AUTO_CREATE_TABLES=false
 
 JWT_SECRET_KEY=change-me-in-production