feat: add Load More pagination to Project Showcase section

[nishupr]

Summary

Closes #639 #634

Scope Note

While investigating this issue, I found that the Resources section (ResourcesTabs.tsx, roadmaps tab) already has a working IntersectionObserver-based infinite scroll implementation (visibleCount, ITEMS_PER_PAGE, observerRef), so no changes were needed there.

The Project Showcase section (ProjectShowcaseSection.tsx), however, was rendering all projects at once with no pagination. This PR addresses that gap.

Changes Made

• Added a visibleCount state initialized to 6 items
• Projects are now sliced (projects.slice(0, visibleCount)) instead of rendering the full list
• Added a "Load More" button that appears only when more projects exist beyond the currently visible count, showing how many remain
• Clicking "Load More" reveals 6 more projects at a time until all are shown

Why this approach?

A "Load More" button was chosen over IntersectionObserver here because:

• It's simpler and avoids adding extra observer/ref boilerplate for what is typically a smaller, finite list (project showcases)
• It matches one of the two acceptable approaches explicitly suggested in the issue
• It keeps the component fully presentational (no other state/side-effects needed)

How to test?

1. Visit a public profile page: /profile/<username>
2. If the user has more than 6 verified projects, only the first 6 should render initially, with a "Load More (X remaining)" button below
3. Clicking the button reveals the next batch of projects until all are visible (button then disappears)
4. If a user has 6 or fewer projects, the button should not appear at all

Type of Change

• Feature (non-breaking)

[Aditya948351]

Great job on the Load More pagination! The component state is handled cleanly, and the slice logic is highly performant for this use case. It perfectly resolves the issue requirements!

Look after passing the Linting check on your next PRs @nishupr