feat(org-chart): implement expandable layout and multi-company navigation

Integrate P5-1B through P5-4 shared Core layout, collapse, zoom/pan/fit, company roots and keyboard accessibility. Include React/HTML examples, virtual 20/100/300 employee fixtures, focused checks and the additive data contract.

packages/org-chart/src/core/expanded-layout.test.ts

@@ -1,29 +1,31 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { expandedPreviewRoots } from './expanded-layout.js';
 import { createOrgChart } from './index.js';
+import { engineTree } from './render.js';
+import type { RenderContext } from './render.js';
 import type { OrganizationTreeNode } from '../data/index.js';
 
-const node = (id: string, parentId: string | null, type: 'root' | 'office' = 'office', children: OrganizationTreeNode[] = []): OrganizationTreeNode => ({
-  organization: { id, parentId, name: id, type, leaderId: null, displayOrder: 0 }, children,
+const node = (id: string, parentId: string | null, children: OrganizationTreeNode[] = []): OrganizationTreeNode => ({
+  organization: { id, parentId, name: id, type: parentId ? 'office' : 'root', leaderId: null, displayOrder: 0 }, children,
 });
 
-test('initial preview keeps actual first-depth ancestry and defers descendants without mutating hierarchy', () => {
-  const grandchild = node('depth-2', 'depth-1');
-  const child = node('depth-1', 'root', 'office', [grandchild]);
-  const roots = [node('root', null, 'root', [child])];
+test('Auto engine projection preserves root, nested ancestry, sibling order and depths without mutation', () => {
+  const roots = [node('root', null, [node('first', 'root', [node('cell', 'first', [node('team', 'cell')])]), node('second', 'root')])];
   const before = structuredClone(roots);
-  const projected = expandedPreviewRoots(roots);
-  assert.deepEqual(projected.map(item => item.organization.id), ['depth-1']);
-  assert.equal(projected[0]!.organization.parentId, 'root');
-  assert.deepEqual(projected[0]!.children, []);
+  const context = { orderedOrganizations: [], readOnly: true } as unknown as RenderContext;
+  const result = engineTree(roots, 'test', context);
+  assert.equal(result[0]?.depth, 0);
+  assert.equal(result[0]?.children?.[0]?.children?.[0]?.children?.[0]?.depth, 3);
+  assert.deepEqual(context.orderedOrganizations.map(item => item.id), ['root', 'first', 'cell', 'team', 'second']);
+  assert.deepEqual(result[0]?.children?.map(item => item.organizationIndex), [1, 4]);
   assert.deepEqual(roots, before);
 });
 
-test('independent roots and normalized order stay independent in the initial preview', () => {
-  const roots = [node('first', null), node('root', null, 'root', [node('second', 'root'), node('third', 'root')])];
-  assert.deepEqual(expandedPreviewRoots(roots).map(item => item.organization.id), ['first', 'second', 'third']);
-  assert.deepEqual(expandedPreviewRoots([]), []);
+test('independent roots remain independent and empty hierarchy stays empty', () => {
+  const context = { orderedOrganizations: [], readOnly: true } as unknown as RenderContext;
+  const roots = [node('first', null), node('second', null)];
+  assert.equal(engineTree(roots, 'test', context).length, 2);
+  assert.deepEqual(engineTree([], 'empty', context), []);
 });
 
 const options = { dataSource: { load: async () => ({}) }, stylesheetUrls: { engine: '/engine.css', core: '/style.css' } };