WebUI 后端类型注解补全，使用全 typing 库类型注解

src/webui/api/replier.py

@@ -8,11 +8,10 @@
 3. 详情按需加载
 """
 
+import json
 from pathlib import Path
 from typing import Dict, List, Optional
 
-import json
-
 from fastapi import APIRouter, Depends, HTTPException, Query
 from pydantic import BaseModel