P10.2: convert remaining dashboardAPI tests from Mocha to node:test

P6.7 converted test/basic/. Convert test/edge/ and test/integration/ the
same way: describe/it/expect → test/assert. No behavioural change.

5 / 5 tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/edge/structure-examples-node-type.edge.test.js

@@ -1,11 +1,11 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
 const fs = require('node:fs');
 const path = require('node:path');
 
 const flow = JSON.parse(fs.readFileSync(path.resolve(__dirname, '../../examples/basic.flow.json'), 'utf8'));
 
-describe('dashboardAPI edge example structure', () => {
-  it('basic example includes node type dashboardapi', () => {
+test('basic example includes node type dashboardapi', () => {
   const count = flow.filter((n) => n && n.type === 'dashboardapi').length;
-    expect(count).toBeGreaterThanOrEqual(1);
-  });
+  assert.ok(count >= 1, `expected ≥1 dashboardapi node, got ${count}`);
 });