修复重构后的导入错误和缺失模块

backend/app/backend.py

@@ -4,7 +4,7 @@ FastAPI 后端 - 支持动态模型切换，使用 PostgreSQL 持久化记忆
 """
 
 import os
-from .config import DB_URI, BACKEND_PORT
+from app.config import DB_URI, BACKEND_PORT
 import uuid
 import json
 from contextlib import asynccontextmanager
@@ -28,7 +28,7 @@ from app.subgraphs.dictionary.api_client import DictionaryAPIClient
 from app.subgraphs.news_analysis.api_client import NewsAPIClient
 from .db.init_db import init_subgraph_tables
 from .db.models import ContactRepository, DictionaryRepository, NewsRepository
-from .logger import info, error
+from app.logger import info, error
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):