fix(hub): keep AI coach page within one viewport

Lock page height and scroll summary/chat inside equal panels instead of extending the document.

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

manual_trading_hub/static/app.js

@@ -647,6 +647,7 @@
     document.querySelectorAll(".page").forEach((el) => {
       el.classList.toggle("hidden", el.id !== pageId);
     });
+    document.body.classList.toggle("hub-page-ai", page === "ai");
     if (page === "monitor") startMonitorPoll();
     else stopMonitorPoll();
     if (page === "settings") loadSettingsUI();