feat: collapse fund overview help and bind start day to env

Fold the stats description by default and render history_start_day and keep_days from the API so HUB_FUND_HISTORY_START_DAY in .env drives the UI.

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

manual_trading_hub/static/funds.js

@@ -11,6 +11,8 @@
   const elDdPct = document.getElementById("funds-total-dd-pct");
   const elDelta = document.getElementById("funds-total-delta");
   const elMeta = document.getElementById("funds-meta");
+  const elDescBody = document.getElementById("funds-desc-body");
+  const elChartSub = document.getElementById("funds-chart-sub");
   const elChartHost = document.getElementById("funds-chart-total");
   const elAccounts = document.getElementById("funds-accounts");
   const elBtnRefresh = document.getElementById("funds-btn-refresh");
@@ -266,7 +268,7 @@
       const parts = [
         "资金户 + 交易户（不含浮盈）",
         "交易日 " + (meta.trading_day || "—"),
-        "自 " + (meta.history_start_day || "2026-06-09") + " 起",
+        "自 " + (meta.history_start_day || "—") + " 起",
       ];
       elFsSub.textContent = parts.join(" · ");
     }
@@ -319,8 +321,28 @@
     }
   }
 
+  function renderDesc(data) {
+    const start = (data && data.history_start_day) || "—";
+    const keep = (data && data.keep_days) || 180;
+    const hour = data && data.reset_hour != null ? data.reset_hour : 8;
+    if (elDescBody) {
+      elDescBody.textContent =
+        "总资金 = 各监控户（资金账户 + 交易账户）；自 " +
+        start +
+        " 起按北京时间 " +
+        hour +
+        ":00 交易日切日快照，最多保留 " +
+        keep +
+        " 天。起算日由环境变量 HUB_FUND_HISTORY_START_DAY 配置。";
+    }
+    if (elChartSub) {
+      elChartSub.textContent = keep + " TRADING DAYS";
+    }
+  }
+
   function renderOverview(data) {
     lastOverview = data;
+    renderDesc(data);
     const totals = data.totals || {};
     const dd = totals.drawdown || {};
     if (elTotal) {
@@ -339,7 +361,7 @@
       const parts = [
         "交易日 " + (data.trading_day || "—"),
         "切日 " + (data.reset_hour != null ? data.reset_hour : 8) + ":00 北京",
-        "自 " + (data.history_start_day || "2026-06-09") + " 起",
+        "自 " + (data.history_start_day || "—") + " 起",
         "最多 " + (data.keep_days || 180) + " 交易日",
       ];
       if (data.updated_at) parts.push("刷新 " + data.updated_at);