Stabilize playground save-shortcut e2e by removing navigation-based URL wait

[Copilot]

The playground website e2e test for Ctrl/Cmd+S intermittently timed out waiting on page.waitForURL(...). The save flow updates query params via same-document URL mutation, so waiting on navigation/load semantics is flaky.

• Root cause addressed: URL update is not a full navigation

  • Replaced waitForURL in ui.e2e.ts with URL polling, which matches the app behavior (history.pushState-style updates).

• E2E assertion update

  • Trigger save first, then assert the encoded c= payload appears in page.url() using expect.poll(...).
  • Preserves the existing encoded-content expectation while removing dependence on load events.

await page.keyboard.press(`${ctrlOrCmd}+KeyS`);
// cspell:disable-next-line
await expect
  .poll(() => page.url())
  .toMatch(new RegExp(`${host}/\\?.*c=b3Agc2hhcmVkQ29kZSgpOiBzdHJpbmc7.*`));

[timotheeguerin]

@copilot format

[Copilot]

@copilot format

Done in b3b5993.

[timotheeguerin]

@copilot fix spellcheck

[Copilot]

@copilot fix spellcheck

Fixed in f50a06b.