fix: 修复or_局部导入遮蔽模块级导入导致UnboundLocalError + Drawer改用size

1. product_service.py: 删除函数内两处 from sqlalchemy import or_
   Python解析器看到函数内的import就把or_当局部变量, 在赋值前使用就报UnboundLocalError
   模块顶部已有 import or_, 函数内无需重复导入

2. AdminDashboard.tsx: Drawer width→size (Antd v6 deprecation)

frontend/src/pages/admin/AdminDashboard.tsx

@@ -412,7 +412,7 @@ export default function AdminDashboard() {
         title={<span className="text-base font-bold">💬 协同留言板 <span className="font-normal text-gray-400">全厂 · {msgTotal} 条</span></span>}
         open={msgDrawerOpen}
         onClose={() => setMsgDrawerOpen(false)}
-        width={560}
+        size="large"
         styles={{ body: { padding: 16, background: "#f8fafc" } }}
       >
         <Input.Search