feat: 添加交易历史、错误提示和打包优化

1. 交易历史记录功能
   - 新增 useTransactionHistory hook 管理交易记录
   - 新增 TransactionHistory 组件显示历史
   - 交易记录保存到 localStorage

2. 错误处理和用户提示
   - 新增 Toast 通知组件
   - 交易提交/成功/失败时显示提示
   - 解析并显示友好的错误信息

3. 打包优化
   - 配置代码分割 (manualChunks)
   - 分离 react/web3/walletconnect/i18n
   - 提高 chunk 大小警告阈值

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/i18n/locales/en.json

@@ -88,6 +88,22 @@
     "en": "English",
     "zh": "Chinese"
   },
+  "history": {
+    "title": "Transaction History",
+    "empty": "No transactions yet",
+    "clear": "Clear",
+    "viewMore": "View More"
+  },
+  "toast": {
+    "txSubmitted": "Transaction submitted",
+    "txSuccess": "Transaction successful",
+    "txFailed": "Transaction failed",
+    "copySuccess": "Copied to clipboard",
+    "walletError": "Wallet error",
+    "networkError": "Network error",
+    "insufficientBalance": "Insufficient balance",
+    "userRejected": "User rejected the transaction"
+  },
   "test": {
     "title": "Boundary Test",
     "currentStatus": "Current Status",