🎨 Palette: Add explicit controls and a11y score announcements to Mario Game

[EiJackGH]

💡 What

• Added visible "Press Space or ↑ to jump" text hint directly beneath the score counter.
• Added aria-live="polite" and aria-atomic="true" attributes to the score display.
• Removed the problematic standard library venv module from requirements.txt to unblock package installation.

🎯 Why

• Players had no visual indication of what keys mapped to the jump action, making the game unapproachable for first-time users.
• The real-time score updates were visually apparent but invisible to assistive technologies.
• pip install -r requirements.txt was failing out-of-the-box due to the venv module.

📸 Before/After

Before: Just a "Score: 0" in the top left, no instructions.
After: "Score: 0" with a subtle, stylistically-matched "Press Space or ↑ to jump" below it.

♿ Accessibility

• Screen Reader Support: Screen readers will now automatically announce changes to the score counter as the player progresses, providing non-visual feedback for game success.
• Cognitive UX: Explicit control text reduces cognitive load and removes guesswork.

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PR created automatically by Jules for task 7199771241939311346 started by @EiJackGH

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