feat: add trading day split lines on hub market chart

Add toggle before technical indicators to show blue dashed vertical lines at Beijing 8:00 day boundaries.

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

manual_trading_hub/static/chart.js

@@ -193,6 +193,8 @@
   const elIndEma = document.getElementById("market-ind-ema");
   const elIndMacd = document.getElementById("market-ind-macd");
   const elIndRsi = document.getElementById("market-ind-rsi");
+  const elDaySplit = document.getElementById("market-day-split");
+  const DAY_SPLIT_STORAGE_KEY = "hub-market-day-split";
   const elFsToolbar = document.getElementById("market-fs-toolbar");
   const elFsExchange = document.getElementById("market-fs-exchange");
   const elFsSymbol = document.getElementById("market-fs-symbol");
@@ -308,6 +310,33 @@
     syncChartWrapLayout();
   }
 
+  function loadDaySplitPref() {
+    try {
+      const raw = localStorage.getItem(DAY_SPLIT_STORAGE_KEY);
+      if (raw === "1" || raw === "true") return true;
+      if (raw === "0" || raw === "false") return false;
+    } catch (_) {}
+    return false;
+  }
+
+  function saveDaySplitPref(on) {
+    try {
+      localStorage.setItem(DAY_SPLIT_STORAGE_KEY, on ? "1" : "0");
+    } catch (_) {}
+  }
+
+  function applyTradingDaySplit(enabled) {
+    if (window.HubChartDraw && typeof window.HubChartDraw.setTradingDaySplit === "function") {
+      window.HubChartDraw.setTradingDaySplit(enabled);
+    }
+  }
+
+  function syncTradingDaySplitUi() {
+    const on = !!(elDaySplit && elDaySplit.checked);
+    saveDaySplitPref(on);
+    applyTradingDaySplit(on);
+  }
+
   function ensureDrawLayer() {
     if (drawAttached || !window.HubChartDraw || !chart || !candleSeries) return;
     window.HubChartDraw.attach({
@@ -322,6 +351,7 @@
       },
     });
     window.HubChartDraw.setViewKey(currentChartViewKey());
+    applyTradingDaySplit(elDaySplit ? elDaySplit.checked : loadDaySplitPref());
     drawAttached = true;
   }
 
@@ -3006,6 +3036,11 @@
         updateIndicators();
       });
     });
+    if (elDaySplit) {
+      elDaySplit.checked = loadDaySplitPref();
+      elDaySplit.addEventListener("change", syncTradingDaySplitUi);
+      applyTradingDaySplit(elDaySplit.checked);
+    }
     const pageMarket = document.getElementById("page-market");
     const fsKeyTargets = [window, pageMarket, elChartWrap, chartHost].filter(Boolean);
     fsKeyTargets.forEach(function (el) {