fix: 修复斗鱼Cookie导出422路由冲突 & 优化登录密码错误提示

- cookies.py: 将 GET /export 路由移至 GET /{task_id} 之前，避免
  动态路径 task_id:int 误匹配 'export' 导致 422 校验错误
- LoginPage.tsx: 密码错误(401)时清空密码框并自动聚焦，方便快速重试
- database.py/migrations/env.py: 应用内嵌调用 alembic 时跳过 fileConfig，
  避免覆盖 uvicorn 日志配置导致启动日志丢失
- client.ts: 401 拦截排除 /auth/login，避免登录失败时误跳转吞掉错误提示

web/frontend/src/api/client.ts

@@ -10,7 +10,9 @@ const api = axios.create({
 api.interceptors.response.use(
   (response) => response.data,
   (error) => {
-    if (error.response?.status === 401) {
+    // 仅在“已登录后 token 失效”时清除登录态并跳转登录页。
+    // 登录接口本身返回 401（用户名/密码错误）时不应跳转，否则会吞掉错误提示。
+    if (error.response?.status === 401 && error.config?.url !== '/auth/login') {
       localStorage.removeItem('user');
       window.location.href = '/login';
     }

web/frontend/src/pages/LoginPage.tsx

@@ -1,5 +1,6 @@
-import { useState } from 'react';
+import { useRef, useState } from 'react';
 import { Card, Form, Input, Button, Typography } from 'antd';
+import type { InputRef } from 'antd';
 import { message } from '../utils/antdMessage';
 import { LockOutlined, UserOutlined } from '@ant-design/icons';
 import { useNavigate } from 'react-router-dom';
@@ -13,6 +14,8 @@ const { Title, Text } = Typography;
 
 export default function LoginPage({ onLogin }: { onLogin?: () => void }) {
   const [loading, setLoading] = useState(false);
+  const [form] = Form.useForm();
+  const passwordRef = useRef<InputRef>(null);
   const navigate = useNavigate();
   const { isDark } = useTheme();
   const appInfo = useAppInfo();
@@ -33,7 +36,13 @@ export default function LoginPage({ onLogin }: { onLogin?: () => void }) {
       onLogin?.();       // 触发 App 重渲染
       navigate('/', { replace: true });
     } catch (e: unknown) {
-      message.error(getErrorMessage(e) || '登录失败');
+      const msg = getErrorMessage(e) || '登录失败';
+      message.error(msg);
+      // 密码错误（401）时清空密码并自动聚焦，方便快速重试
+      if (msg.includes('密码') || msg.includes('用户名')) {
+        form.setFieldValue('password', '');
+        passwordRef.current?.focus();
+      }
     } finally {
       setLoading(false);
     }
@@ -62,12 +71,12 @@ export default function LoginPage({ onLogin }: { onLogin?: () => void }) {
         }}>
           当前版本 {versionText}
         </Text>
-        <Form onFinish={onFinish} size="large">
+        <Form form={form} onFinish={onFinish} size="large">
           <Form.Item name="username" rules={[{ required: true, message: '请输入用户名' }]}>
             <Input prefix={<UserOutlined />} placeholder="用户名" />
           </Form.Item>
           <Form.Item name="password" rules={[{ required: true, message: '请输入密码' }]}>
-            <Input.Password prefix={<LockOutlined />} placeholder="密码" />
+            <Input.Password prefix={<LockOutlined />} placeholder="密码" ref={passwordRef} />
           </Form.Item>
           <Form.Item>
             <Button type="primary" htmlType="submit" loading={loading} block>