feat: add CSS-only Tooltip demo with delay and fade-in effect + Demo video

[rohitmane01]

What this PR does

• Adds a new CSS-only Tooltip demo with a delay effect.
• Tooltip fades in after 0.5s when hovering or focusing on the target element.
• Includes arrow styling for a polished look.

Why

• Tooltips are commonly implemented with JavaScript, especially when a delay is required.
• This demo showcases how the same effect can be achieved with pure CSS transitions and delay properties.
• Enhances the collection by adding a practical, widely used UI pattern.

Features

• Pure CSS implementation (no JS).
• Works on both hover and focus (better accessibility).
• Customizable delay via transition-delay.
• Responsive and lightweight.

Notes

• Tested in Chrome, Firefox, and Edge.
• Mobile long-press support may vary by browser.

Demo Video

Screen.Recording.2025-10-04.204701.mp4

[aayush105]

Thank you @rohitmane01 for your contribution.