feat: 实现 Builder API Key 系统级配置和 Gasless 交易支持

- 新增系统配置表（SystemConfig）用于存储 Builder API Key
- 实现 Builder API Key 的前端配置页面
- 集成 Builder Relayer API 支持 Gasless 交易
- 在 API 健康检查中添加 Builder Relayer API 检测
- 移除前端 API 测试功能，简化配置页面
- 修复赎回仓位时的 Builder API Key 检查逻辑
- 更新错误处理，引导用户配置 Builder API Key

frontend/src/pages/BuilderApiKeySettings.tsx

@@ -0,0 +1,165 @@
+import { useEffect, useState } from 'react'
+import { Card, Form, Button, Input, message, Typography, Space, Alert } from 'antd'
+import { SaveOutlined, LinkOutlined } from '@ant-design/icons'
+import { apiService } from '../services/api'
+import { useMediaQuery } from 'react-responsive'
+import { useTranslation } from 'react-i18next'
+import type { SystemConfig, BuilderApiKeyUpdateRequest } from '../types'
+
+const { Title, Paragraph, Text } = Typography
+
+const BuilderApiKeySettings: React.FC = () => {
+  const { t } = useTranslation()
+  const isMobile = useMediaQuery({ maxWidth: 768 })
+  const [builderApiKeyForm] = Form.useForm()
+  const [builderApiKeyConfig, setBuilderApiKeyConfig] = useState<SystemConfig | null>(null)
+  const [builderApiKeyLoading, setBuilderApiKeyLoading] = useState(false)
+  
+  useEffect(() => {
+    fetchBuilderApiKeyConfig()
+  }, [])
+  
+  const fetchBuilderApiKeyConfig = async () => {
+    try {
+      const response = await apiService.systemConfig.get()
+      if (response.data.code === 0 && response.data.data) {
+        const config = response.data.data
+        setBuilderApiKeyConfig(config)
+        // 预填充字段（如果已配置，显示占位符）
+        builderApiKeyForm.setFieldsValue({
+          builderApiKey: config.builderApiKeyConfigured ? '***' : '',
+          builderSecret: config.builderSecretConfigured ? '***' : '',
+          builderPassphrase: config.builderPassphraseConfigured ? '***' : '',
+        })
+      } else {
+        message.error(response.data.msg || t('builderApiKey.getFailed'))
+      }
+    } catch (error: any) {
+      message.error(error.message || t('builderApiKey.getFailed'))
+    }
+  }
+  
+  const handleBuilderApiKeySubmit = async (values: BuilderApiKeyUpdateRequest) => {
+    setBuilderApiKeyLoading(true)
+    try {
+      // 如果值是 '***'，表示已配置但未修改，不发送
+      const updateData: BuilderApiKeyUpdateRequest = {}
+      if (values.builderApiKey && values.builderApiKey !== '***') {
+        updateData.builderApiKey = values.builderApiKey
+      }
+      if (values.builderSecret && values.builderSecret !== '***') {
+        updateData.builderSecret = values.builderSecret
+      }
+      if (values.builderPassphrase && values.builderPassphrase !== '***') {
+        updateData.builderPassphrase = values.builderPassphrase
+      }
+      
+      const response = await apiService.systemConfig.updateBuilderApiKey(updateData)
+      if (response.data.code === 0) {
+        message.success(t('builderApiKey.saveSuccess'))
+        fetchBuilderApiKeyConfig()
+      } else {
+        message.error(response.data.msg || t('builderApiKey.saveFailed'))
+      }
+    } catch (error: any) {
+      message.error(error.message || t('builderApiKey.saveFailed'))
+    } finally {
+      setBuilderApiKeyLoading(false)
+    }
+  }
+  
+  return (
+    <div>
+      <div style={{ marginBottom: '16px' }}>
+        <Title level={2} style={{ margin: 0 }}>{t('builderApiKey.title')}</Title>
+      </div>
+      
+      <Card>
+        <Alert
+          message={t('builderApiKey.alertTitle')}
+          description={
+            <div>
+              <Paragraph style={{ marginBottom: '8px' }}>
+                {t('builderApiKey.description')}
+              </Paragraph>
+              <Paragraph style={{ marginBottom: '8px' }}>
+                <Text strong>{t('builderApiKey.purposeTitle')}</Text>
+                <ul style={{ marginTop: '8px', marginBottom: 0, paddingLeft: '20px' }}>
+                  <li>{t('builderApiKey.purpose1')}</li>
+                  <li>{t('builderApiKey.purpose2')}</li>
+                  <li>{t('builderApiKey.purpose3')}</li>
+                </ul>
+              </Paragraph>
+              <Paragraph style={{ marginBottom: 0 }}>
+                <Text strong>{t('builderApiKey.getApiKey')}</Text>
+                <Space style={{ marginLeft: '8px' }}>
+                  <a 
+                    href="https://polymarket.com/settings?tab=builder" 
+                    target="_blank" 
+                    rel="noopener noreferrer"
+                  >
+                    <LinkOutlined /> {t('builderApiKey.openSettings')}
+                  </a>
+                </Space>
+              </Paragraph>
+            </div>
+          }
+          type="info"
+          showIcon
+          style={{ marginBottom: '24px' }}
+        />
+        
+        <Form
+          form={builderApiKeyForm}
+          layout="vertical"
+          onFinish={handleBuilderApiKeySubmit}
+          size={isMobile ? 'middle' : 'large'}
+        >
+          <Form.Item
+            label={t('builderApiKey.apiKey')}
+            name="builderApiKey"
+            help={builderApiKeyConfig?.builderApiKeyConfigured ? t('builderApiKey.apiKeyHelp') : t('builderApiKey.apiKeyPlaceholder')}
+          >
+            <Input 
+              placeholder={builderApiKeyConfig?.builderApiKeyConfigured ? t('builderApiKey.apiKeyHelp') : t('builderApiKey.apiKeyPlaceholder')}
+            />
+          </Form.Item>
+          
+          <Form.Item
+            label={t('builderApiKey.secret')}
+            name="builderSecret"
+            help={builderApiKeyConfig?.builderSecretConfigured ? t('builderApiKey.secretHelp') : t('builderApiKey.secretPlaceholder')}
+          >
+            <Input 
+              placeholder={builderApiKeyConfig?.builderSecretConfigured ? t('builderApiKey.secretHelp') : t('builderApiKey.secretPlaceholder')}
+            />
+          </Form.Item>
+          
+          <Form.Item
+            label={t('builderApiKey.passphrase')}
+            name="builderPassphrase"
+            help={builderApiKeyConfig?.builderPassphraseConfigured ? t('builderApiKey.passphraseHelp') : t('builderApiKey.passphrasePlaceholder')}
+          >
+            <Input 
+              placeholder={builderApiKeyConfig?.builderPassphraseConfigured ? t('builderApiKey.passphraseHelp') : t('builderApiKey.passphrasePlaceholder')}
+            />
+          </Form.Item>
+          
+          <Form.Item>
+            <Button
+              type="primary"
+              htmlType="submit"
+              icon={<SaveOutlined />}
+              loading={builderApiKeyLoading}
+            >
+              {t('common.save') || '保存配置'}
+            </Button>
+          </Form.Item>
+        </Form>
+      </Card>
+    </div>
+  )
+}
+
+export default BuilderApiKeySettings
+

frontend/src/pages/PositionList.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useState, useMemo } from 'react'
 import { Card, Table, Tag, message, Space, Input, Radio, Select, Button, Row, Col, Empty, Modal, Form, Descriptions } from 'antd'
 import { SearchOutlined, AppstoreOutlined, UnorderedListOutlined, UpOutlined, DownOutlined } from '@ant-design/icons'
+import { useNavigate } from 'react-router-dom'
 import { apiService } from '../services/api'
 import type { AccountPosition, Account, PositionPushMessage, PositionSellRequest, MarketPriceResponse, RedeemablePositionsSummary, PositionRedeemRequest } from '../types'
 import { getPositionKey } from '../types'
@@ -13,6 +14,7 @@ type PositionFilter = 'current' | 'historical'
 type ViewMode = 'card' | 'list'
 
 const PositionList: React.FC = () => {
+  const navigate = useNavigate()
   const isMobile = useMediaQuery({ maxWidth: 768 })
   const [currentPositions, setCurrentPositions] = useState<AccountPosition[]>([])
   const [historyPositions, setHistoryPositions] = useState<AccountPosition[]>([])
@@ -113,10 +115,34 @@ const PositionList: React.FC = () => {
         // 刷新可赎回统计
         await fetchRedeemableSummary()
       } else {
-        message.error(response.data.msg || '赎回失败')
+        // 检查是否是 Builder API Key 未配置的错误
+        if (response.data.code === 2014 || response.data.msg?.includes('Builder API Key 未配置')) {
+          message.error({
+            content: response.data.msg || 'Builder API Key 未配置',
+            duration: 5,
+          })
+          // 延迟跳转，让用户看到错误消息
+          setTimeout(() => {
+            navigate('/system-settings/builder-api-key')
+          }, 1500)
+        } else {
+          message.error(response.data.msg || '赎回失败')
+        }
       }
     } catch (error: any) {
-      message.error('赎回失败: ' + (error.message || '未知错误'))
+      // 检查是否是 Builder API Key 未配置的错误
+      if (error.response?.data?.code === 2014 || error.message?.includes('Builder API Key 未配置')) {
+        message.error({
+          content: error.response?.data?.msg || error.message || 'Builder API Key 未配置，请前往系统设置页面配置',
+          duration: 5,
+        })
+        // 延迟跳转，让用户看到错误消息
+        setTimeout(() => {
+          navigate('/system-settings/builder-api-key')
+        }, 1500)
+      } else {
+        message.error('赎回失败: ' + (error.message || '未知错误'))
+      }
     } finally {
       setRedeeming(false)
     }