feat: hub setting to hide account balances and PnL in monitor

Persist show_account_pnl in hub_settings.json; refine key monitor panel layout with right-aligned live stats and scrollable history (max 8 rows).

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

manual_trading_hub/static/index.html

@@ -466,6 +466,14 @@
         </div>
       </details>
       <p id="settings-meta-line" class="settings-meta-line"></p>
+      <div class="settings-display-panel card">
+        <h3 class="settings-display-title">监控区显示</h3>
+        <label class="chk-label settings-display-chk">
+          <input type="checkbox" id="pref-show-account-pnl" checked />
+          显示资金账户、交易账户与浮动盈亏
+        </label>
+        <p class="settings-display-hint">关闭后监控区不显示上述数值；保存至 hub_settings.json，换浏览器同样生效。</p>
+      </div>
       <div class="toolbar">
         <button type="button" id="btn-settings-save" class="primary">保存设置</button>
         <button type="button" id="btn-settings-add">添加交易所</button>