🎨 Palette: [UX improvement] Add keyboard instructions and ARIA score announcements to Mario Game

[EiJackGH]

💡 What

Added visible instructional text below the score in mario-game.njk to clarify keyboard controls ("Press Space or Up Arrow to jump"). Added aria-live="polite" and aria-atomic="true" attributes to the score display element.

🎯 Why

Previously, the game loaded without any indication of how to play, which could confuse users. Additionally, the score updates were visual-only, making the game's progress inaccessible to screen reader users.

📸 Before/After

(Visual changes verified via Playwright screenshot during development. The instructions text appears neatly beneath the score counter.)

♿ Accessibility

• Screen Reader Support: The score element now acts as a live region (aria-live="polite"), meaning assistive technologies will announce the score as it increments when Goombas are avoided.
• Keyboard Discoverability: Explicit text instructions ensure users know which keys to press, rather than having to guess. The static instructions were kept outside of the aria-live region so they are not needlessly repeated on every score change.

---

PR created automatically by Jules for task 2789820723272851070 started by @EiJackGH

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.