feat(UI): animate activated link hint (scale + fade-out) before cleanup

[geekbrother]

Description

Adds a brief animation to the activated hint: it scales up and fades out while non-activated hints are hidden immediately.
Hint markers are removed only after the animation completes.

Motivation

Provides clearer visual confirmation of the chosen hint and improves perceived polish without impacting interaction speed.

User-facing behavior

• Before: All hint markers disappeared instantly upon activation.
• After: The selected hint remains, scales to 1.5x, and fades to 0 opacity over the configured duration; others are hidden instantly. All markers are removed once the animation finishes.

Testing

Open any page, trigger hints (f), choose a hint: activated marker should scale+fade while others hide immediately; markers should then be removed.
Validate no lingering elements or pointer-event issues post-animation.

[geekbrother]

cc @philc @philg-dev for a review 🙏