fix(hub): use single position table header on desktop monitor cards

Render all exchange positions in one table row group instead of repeating column headers per symbol.

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

manual_trading_hub/static/index.html

@@ -246,6 +246,6 @@
   <div id="toast"></div>
   <script src="https://unpkg.com/lightweight-charts@4.2.0/dist/lightweight-charts.standalone.production.js"></script>
   <script src="/assets/chart.js?v=20260603-hub-binance-tick"></script>
-  <script src="/assets/app.js?v=20260604-hub-grid-compact2"></script>
+  <script src="/assets/app.js?v=20260604-hub-pos-table"></script>
 </body>
 </html>