fix: 修复 walletType 字段问题和 WebSocket 内存泄漏，优化账户导入 UI

后端修复：
- 添加 walletType 字段到 Account 实体和数据库（V17 迁移）
- 修复 refreshProxyAddress 方法使用正确的 walletType
- 修复 WebSocketTicketService 内存泄漏（添加定时清理任务）

前端优化：
- 账户导入改为 Modal 弹窗，提升用户体验
- 默认钱包类型改为 Web3 Wallet（safe），并将其选项排在首位
- 更新多语言文本：将 MetaMask（浏览器钱包）改为 Web3钱包
- 修复 walletTypeHelp Tooltip 换行显示问题

frontend/src/locales/en/common.json

@@ -201,9 +201,9 @@
     "addressError": "Cannot derive address from private key",
     "addressErrorMnemonic": "Cannot derive address from mnemonic",
     "walletType": "Wallet Type",
-    "walletTypeHelp": "Magic: Polymarket accounts logged in via email or social accounts (Google, Twitter, etc.); MetaMask: Polymarket accounts connected via browser wallets like MetaMask",
+    "walletTypeHelp": "Web3 Wallet: Polymarket accounts connected via browser wallets like MetaMask\nMagic: Polymarket accounts logged in via email or social accounts (Google, Twitter, etc.)",
     "walletTypeMagic": "Magic (Email/Social Login)",
-    "walletTypeSafe": "MetaMask (Browser Wallet)"
+    "walletTypeSafe": "Web3 Wallet"
   },
   "leader": {
     "title": "Leader Management",