feat: Implement basic general folder support (#2051)

- Related: #1748

src/ha/panel.ts

@@ -0,0 +1,11 @@
+/**
+ * Determine if a card is in panel mode.
+ */
+export const isCardInPanel = (card: HTMLElement): boolean => {
+  const parent = card.getRootNode();
+  return !!(
+    parent &&
+    parent instanceof ShadowRoot &&
+    parent.host.tagName === 'HUI-PANEL-VIEW'
+  );
+};