[eric] palettes: portal Cmd+K and Cmd+F to a body top layer so cards stop painting over them

frontend/src/shared/TopLayerPortal.tsx

@@ -0,0 +1,16 @@
+import React from 'react';
+import { createPortal } from 'react-dom';
+
+// A low-z or transformed ancestor traps position:fixed, so anything that must win every stacking fight mounts on body instead.
+const TOP_LAYER = 2147483647;
+
+interface Props {
+  children: React.ReactNode;
+}
+
+const TopLayerPortal: React.FC<Props> = ({ children }) => createPortal(
+  <div style={{ position: 'fixed', inset: 0, zIndex: TOP_LAYER }}>{children}</div>,
+  document.body,
+);
+
+export default TopLayerPortal;