Auto-size hub order popup iframe so trade form shows without scrollbars.

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

static/instance_embed.js

@@ -35,6 +35,22 @@
     } catch (_) {}
   }
 
+  function reportOrderPopupSize() {
+    if (!isOrderPopup()) return;
+    const root = document.querySelector(".embed-order-popup-shell") || document.body;
+    const h = Math.ceil(
+      Math.max(
+        root.scrollHeight,
+        root.offsetHeight,
+        document.documentElement.scrollHeight,
+        document.body.scrollHeight
+      )
+    );
+    try {
+      window.parent.postMessage({ type: "hub-order-popup-resize", height: h }, "*");
+    } catch (_) {}
+  }
+
   function prefillOrderSymbolFromQuery() {
     if (!isOrderPopup()) return;
     let sym = "";
@@ -109,6 +125,7 @@
     if (typeof global.refreshPriceSnapshotConditional === "function") {
       global.refreshPriceSnapshotConditional();
     }
+    reportOrderPopupSize();
   }
 
   function injectFragment(html) {
@@ -280,6 +297,17 @@
     patchHardNavigations();
     bindNav();
     runPageInit(getTab());
+    reportOrderPopupSize();
+    if (isOrderPopup()) {
+      window.setTimeout(reportOrderPopupSize, 120);
+      window.setTimeout(reportOrderPopupSize, 450);
+      if (typeof ResizeObserver !== "undefined") {
+        const root = document.querySelector(".embed-order-popup-shell") || document.body;
+        try {
+          new ResizeObserver(() => reportOrderPopupSize()).observe(root);
+        } catch (_) {}
+      }
+    }
     try {
       window.parent.postMessage({ type: "instance-frame-ready" }, "*");
     } catch (_) {}