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/locales/zh-CN/common.json

@@ -150,8 +150,10 @@
     "statistics": "统计信息",
     "users": "用户管理",
     "systemSettings": "系统管理",
+    "systemOverview": "概览",
     "language": "语言",
     "apiHealth": "API健康",
+    "builderApiKey": "Builder API Key",
     "proxy": "代理",
     "notifications": "消息推送",
     "logout": "退出登录",
@@ -214,6 +216,49 @@
     "systemSettingsDesc": "配置代理、查看 API 健康状态",
     "footer": "请使用上述页面进行配置管理。"
   },
+  "builderApiKey": {
+    "title": "Builder API Key 配置",
+    "alertTitle": "什么是 Builder API Key？",
+    "description": "Builder API Key 是系统级别的配置，与您的账户无关。它是 Polymarket 提供的 Builder 服务的 API 凭证，用于执行 Gasless（免 gas 费）交易。",
+    "purposeTitle": "主要用途：",
+    "purpose1": "执行 Gasless 交易：赎回仓位、创建订单等操作无需支付 gas 费用",
+    "purpose2": "提升用户体验：无需在钱包中准备 MATIC 代币作为 gas 费",
+    "purpose3": "降低交易成本：由 Builder 服务承担 gas 费用",
+    "getApiKey": "获取 API Key：",
+    "openSettings": "前往 Polymarket 设置页面",
+    "apiKey": "Builder API Key",
+    "secret": "Builder Secret",
+    "passphrase": "Builder Passphrase",
+    "apiKeyPlaceholder": "请输入 Builder API Key",
+    "secretPlaceholder": "请输入 Builder Secret",
+    "passphrasePlaceholder": "请输入 Builder Passphrase",
+    "apiKeyHelp": "已配置，输入新值以更新",
+    "secretHelp": "已配置，输入新值以更新",
+    "passphraseHelp": "已配置，输入新值以更新",
+    "saveSuccess": "保存 Builder API Key 配置成功",
+    "saveFailed": "保存 Builder API Key 配置失败",
+    "getFailed": "获取 Builder API Key 配置失败",
+    "notConfigured": "Builder API Key 未配置，请前往系统设置页面配置",
+    "notConfiguredError": "Builder API Key 未配置，无法执行 Gasless 交易。请前往系统设置页面配置 Builder API Key。",
+    "apiReference": "API 参考文档",
+    "apiReferenceDesc": "了解更多关于 Builder API 的使用方法：",
+    "relayerApiDocs": "Builder Relayer API 文档",
+    "builderDocs": "Builder 开发文档",
+    "apiTest": "API 测试",
+    "apiTestDesc": "测试 Builder API 是否正常工作",
+    "testNonce": "测试获取 Nonce",
+    "testNonceHelp": "输入 Safe 地址（proxyAddress）",
+    "testDeployed": "测试检查部署状态",
+    "testDeployedHelp": "输入 Safe 地址（proxyAddress）",
+    "testTransaction": "测试获取交易状态",
+    "testTransactionHelp": "输入交易ID",
+    "testAddressRequired": "请输入地址",
+    "testTransactionIdRequired": "请输入交易ID",
+    "testAddressPlaceholder": "输入地址，例如：0x...",
+    "testTransactionIdPlaceholder": "输入交易ID",
+    "testSuccess": "测试成功",
+    "testFailed": "测试失败"
+  },
   "resetPassword": {
     "title": "重置密码",
     "firstUse": "首次使用系统",