test(app): cover overlapping floating panel host lifetimes

Exercise surviving host measurement through real portal components after the newest host unmounts.

Co-authored-by: likaixuan <likaixuan@mucang.cn>

packages/app/src/components/ui/floating-panel-overlap.browser.test.tsx

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+import React, { act } from "react";
+import { createRoot } from "react-dom/client";
+import { describe, expect, test } from "vitest";
+import { Portal, PortalProvider } from "@gorhom/portal";
+import { FloatingPanelPortalHost, measureFloatingPanelPortalHost } from "./floating-panel-portal";
+
+describe("Floating panel host lifetime", () => {
+  test("removing the newest host preserves the surviving host measurement", async () => {
+    const container = document.createElement("div");
+    container.style.cssText = "position:relative;width:800px;height:600px";
+    document.body.appendChild(container);
+    const root = createRoot(container);
+    function Content({ overlap }: { overlap: boolean }) {
+      return (
+        <PortalProvider shouldAddRootHost={false}>
+          <FloatingPanelPortalHost name="workspace" />
+          {overlap && <FloatingPanelPortalHost name="workspace" />}
+          <Portal hostName="workspace" name="picker">
+            <div data-testid="picker">Commands</div>
+          </Portal>
+        </PortalProvider>
+      );
+    }
+    try {
+      await act(async () => root.render(<Content overlap={true} />));
+      expect(await measureFloatingPanelPortalHost("workspace")).toMatchObject({
+        width: 800,
+        height: 600,
+      });
+      await act(async () => root.render(<Content overlap={false} />));
+      expect(await measureFloatingPanelPortalHost("workspace")).toMatchObject({
+        width: 800,
+        height: 600,
+      });
+    } finally {
+      await act(async () => root.unmount());
+      container.remove();
+    }
+  });
+});