feat(crypto-tail): 尾盘策略页币安 API 状态监控与重连间隔调整

- 尾盘策略页：进入时检测币安 API/WebSocket，异常时红色强提醒
- 异常时提供「重新检测」按钮，不跳转 API 健康页、不做 60s 轮询
- 文案面向小白：无法连接币安 API、需行情数据、稍后重新检测
- 多语言：zh-CN/zh-TW/en 新增 cryptoTailStrategy.binanceApiAlert
- 币安 K 线 WS 重连延迟由 10s 改为 3s

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/locales/en/common.json

@@ -1402,6 +1402,11 @@
     "rerunFailed": "Re-run failed"
   },
   "cryptoTailStrategy": {
+    "binanceApiAlert": {
+      "title": "Cannot connect to Binance API — strategy cannot run for now",
+      "description": "Tail strategy needs Binance market data to work. The connection failed; this may be a network issue or Binance outage. Try again later by clicking the button below.",
+      "recheck": "Re-check"
+    },
     "list": {
       "title": "Crypto Tail Strategy",
       "walletTip": "Use a dedicated wallet for tail strategy. Do not use it for manual trading or copy trading to avoid balance/position issues.",