fix(langgraph): 支持通过环境变量关闭定时全量同步

cfc-langgraph/app/main.py

@@ -74,8 +74,11 @@ async def startup():
                 logger.warning("知识库同步失败: %s", e)
             await asyncio.sleep(3600)
 
-    asyncio.create_task(schedule_kb_sync())
-    logger.info("知识库定时同步已启动 (首次延迟 120s，间隔 3600s)")
+    if os.getenv("KB_SYNC_ENABLED", "true").lower() == "false":
+        logger.info("知识库定时同步已禁用 (KB_SYNC_ENABLED=false)")
+    else:
+        asyncio.create_task(schedule_kb_sync())
+        logger.info("知识库定时同步已启动 (首次延迟 120s，间隔 3600s)")
 
 
 @app.on_event("shutdown")