Add slide-up/slide-down animations for modal open/close and improve overlay fade

[MOSHKA-GOT]

Description

This PR updates the modal component to improve UX by adding open and close animations for both the modal content and the overlay background.

• CodeExamples.tsx:

  • Removed conditional rendering of CodeModal to allow close animation before unmounting.

• dialog-modal.tsx:

  • Replaced animate-contentShow with slide-up and slide-down animations.
  • Added overlay-fade-out animation for smooth background disappearance.
  • Adjusted overlay positioning (grid place-items-end, overflow-hidden).

These changes ensure that when the modal closes, it slides down instead of disappearing abruptly.

Before / After

▶ Before (open/close without smooth close)

1.mp4

▶ After (slide-up on open, slide-down on close, overlay fade)

2.mp4

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Lighthouse	7 paths audited Performance: 54 (no change from production) Accessibility: 94 (🔴 down 1 from production) Best Practices: 92 (no change from production) SEO: 99 (no change from production) PWA: 59 (no change from production) View the detailed breakdown and full score reports

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[MOSHKA-GOT]

@chuyeow @matthieu @shazow @fjl Hey team, mind giving this PR a review?

[MOSHKA-GOT]

@chuyeow @matthieu @shazow @fjl Hello team, would you be able to review this PR?

[wackerow]

@pettinarip Mind giving this a review from a performance stand point?