Fix run-demo-interaction-bench: replace broken DOM selectors with correct UI interactions

[Copilot]

setDemoControls was written against a UI that doesn't exist — it called page.select() on radio buttons/range-slider and clicked a #generateBtn that was never in index.html, so the demo bench script was entirely non-functional.

Changes

• setDemoControls rewritten to match the actual index.html / app.ts UI:
  • Geometry & renderer set via input[name="…"] radio buttons (checked = true + change event)
  • Point count set by snapping to nearest POINT_PRESETS entry, writing to the #numPoints range slider, and firing input + change to trigger the app's debounced generateAndLoad()
  • #generateBtn click removed — auto-generation is driven by the control events
  • waitForFunction now compares against actualPoints (the snapped preset) so it correctly matches what #statPoints will display

// Before — broken: no <select> or #generateBtn exists in the demo page
await page.select('#geometry', cfg.geometry);
await page.select('#numPoints', String(cfg.points));
await page.click('#generateBtn');

// After — correct: interact with radio buttons + range slider
await page.evaluate((geometry) => {
  const el = document.querySelector<HTMLInputElement>(`input[name="geometry"][value="${geometry}"]`);
  if (el) { el.checked = true; el.dispatchEvent(new Event('change', { bubbles: true })); }
}, cfg.geometry);
// … similarly for renderer + numPoints slider

Original prompt

make sure the full example including the agent runs. see the new demo scripts in the main branch and use the same dataset...

and make sure the example works well

The user has attached the following file paths as relevant context:

• AGENTS.md

Created from VS Code.

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