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.",

frontend/src/locales/zh-CN/common.json

@@ -1401,6 +1401,11 @@
     "rerunFailed": "重新测试失败"
   },
   "cryptoTailStrategy": {
+    "binanceApiAlert": {
+      "title": "无法连接币安 API，策略暂时不能运行",
+      "description": "尾盘策略需要从币安获取行情数据才能工作。当前连接失败，可能是网络问题或币安服务异常，请稍后点击下方按钮重新检测。",
+      "recheck": "重新检测"
+    },
     "list": {
       "title": "加密尾盘策略",
       "walletTip": "请使用单独的钱包运行尾盘策略，避免该钱包用于手动交易、跟单等其他操作，否则可能导致余额或仓位变化，造成策略执行异常。",

frontend/src/locales/zh-TW/common.json

@@ -1402,6 +1402,11 @@
     "rerunFailed": "重新測試失敗"
   },
   "cryptoTailStrategy": {
+    "binanceApiAlert": {
+      "title": "無法連接幣安 API，策略暫時不能運行",
+      "description": "尾盤策略需要從幣安取得行情資料才能運作。目前連線失敗，可能是網路問題或幣安服務異常，請稍後點擊下方按鈕重新檢測。",
+      "recheck": "重新檢測"
+    },
     "list": {
       "title": "加密尾盤策略",
       "walletTip": "請使用單獨的錢包運行尾盤策略，避免該錢包用於手動交易、跟單等其他操作，否則可能導致餘額或倉位變化，造成策略執行異常。",