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-TW/common.json

@@ -233,8 +233,10 @@
     "statistics": "統計信息",
     "users": "用戶管理",
     "systemSettings": "系統管理",
+    "systemOverview": "概覽",
     "language": "語言",
     "apiHealth": "API健康",
+    "builderApiKey": "Builder API Key",
     "proxy": "代理",
     "notifications": "消息推送",
     "logout": "退出登錄",
@@ -302,6 +304,49 @@
     "systemSettingsDesc": "配置代理、查看 API 健康狀態",
     "footer": "請使用上述頁面進行配置管理。"
   },
+  "builderApiKey": {
+    "title": "Builder API Key 配置",
+    "alertTitle": "什麼是 Builder API Key？",
+    "description": "Builder API Key 是系統級別的配置，與您的賬戶無關。它是 Polymarket 提供的 Builder 服務的 API 憑證，用於執行 Gasless（免 gas 費）交易。",
+    "purposeTitle": "主要用途：",
+    "purpose1": "執行 Gasless 交易：贖回倉位、創建訂單等操作無需支付 gas 費用",
+    "purpose2": "提升用戶體驗：無需在錢包中準備 MATIC 代幣作為 gas 費",
+    "purpose3": "降低交易成本：由 Builder 服務承擔 gas 費用",
+    "getApiKey": "獲取 API Key：",
+    "openSettings": "前往 Polymarket 設置頁面",
+    "apiKey": "Builder API Key",
+    "secret": "Builder Secret",
+    "passphrase": "Builder Passphrase",
+    "apiKeyPlaceholder": "請輸入 Builder API Key",
+    "secretPlaceholder": "請輸入 Builder Secret",
+    "passphrasePlaceholder": "請輸入 Builder Passphrase",
+    "apiKeyHelp": "已配置，輸入新值以更新",
+    "secretHelp": "已配置，輸入新值以更新",
+    "passphraseHelp": "已配置，輸入新值以更新",
+    "saveSuccess": "保存 Builder API Key 配置成功",
+    "saveFailed": "保存 Builder API Key 配置失敗",
+    "getFailed": "獲取 Builder API Key 配置失敗",
+    "notConfigured": "Builder API Key 未配置，請前往系統設置頁面配置",
+    "notConfiguredError": "Builder API Key 未配置，無法執行 Gasless 交易。請前往系統設置頁面配置 Builder API Key。",
+    "apiReference": "API 參考文檔",
+    "apiReferenceDesc": "了解更多關於 Builder API 的使用方法：",
+    "relayerApiDocs": "Builder Relayer API 文檔",
+    "builderDocs": "Builder 開發文檔",
+    "apiTest": "API 測試",
+    "apiTestDesc": "測試 Builder API 是否正常工作",
+    "testNonce": "測試獲取 Nonce",
+    "testNonceHelp": "輸入 Safe 地址（proxyAddress）",
+    "testDeployed": "測試檢查部署狀態",
+    "testDeployedHelp": "輸入 Safe 地址（proxyAddress）",
+    "testTransaction": "測試獲取交易狀態",
+    "testTransactionHelp": "輸入交易ID",
+    "testAddressRequired": "請輸入地址",
+    "testTransactionIdRequired": "請輸入交易ID",
+    "testAddressPlaceholder": "輸入地址，例如：0x...",
+    "testTransactionIdPlaceholder": "輸入交易ID",
+    "testSuccess": "測試成功",
+    "testFailed": "測試失敗"
+  },
   "resetPassword": {
     "title": "重置密碼",
     "firstUse": "首次使用系統",