feat: rudimentary menu working now

tests/renderer/components/menuInsertTarget.test.ts

@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest';
+
+import type { MenuItemData } from '../../../src/main/shared/electronApi';
+import { resolveInsertTarget } from '../../../src/renderer/components/MenuEditorView/menuInsertTarget';
+
+function createTree(): MenuItemData[] {
+  return [
+    {
+      id: 'home',
+      title: 'Home',
+      kind: 'page',
+      children: [],
+    },
+    {
+      id: 'docs',
+      title: 'Docs',
+      kind: 'submenu',
+      children: [
+        {
+          id: 'about',
+          title: 'About',
+          kind: 'page',
+          children: [],
+        },
+      ],
+    },
+  ];
+}
+
+describe('resolveInsertTarget', () => {
+  it('inserts on root level when no selection exists', () => {
+    const result = resolveInsertTarget(createTree(), null);
+    expect(result).toEqual({ parentPath: [], index: 2 });
+  });
+
+  it('inserts as first child when selected node is submenu', () => {
+    const result = resolveInsertTarget(createTree(), 'docs');
+    expect(result).toEqual({ parentPath: [1], index: 0 });
+  });
+
+  it('inserts as next sibling when selected node is page', () => {
+    const result = resolveInsertTarget(createTree(), 'home');
+    expect(result).toEqual({ parentPath: [], index: 1 });
+  });
+});