修复代码，实现rag测试

tools/test/test_fast_rag_fix.py

@@ -2,21 +2,12 @@
 """
 快速测试 - 测试 fast_rag 路径修复
 """
-import sys
+
 import asyncio
-from pathlib import Path
-from dotenv import load_dotenv
-
-# 路径设置
-project_root = Path(__file__).resolve().parent.parent
-sys.path.insert(0, str(project_root))
-sys.path.insert(0, str(project_root / "backend"))
-load_dotenv(project_root / ".env")
-
-from app.main_graph.state import MainGraphState, CurrentAction
-from app.main_graph.utils.main_graph_builder import build_react_main_graph
-from app.model_services.chat_services import get_all_chat_services
-from app.main_graph.tools.graph_tools import AVAILABLE_TOOLS
+from backend.app.main_graph.state import MainGraphState, CurrentAction
+from backend.app.main_graph.utils.main_graph_builder import build_react_main_graph
+from backend.app.model_services.chat_services import get_all_chat_services
+from backend.app.main_graph.tools.graph_tools import AVAILABLE_TOOLS
 
 
 async def test_fast_rag_path():