[Frontend] Implement infinite scroll for course listings

[jobbykings]

Summary

Replace traditional pagination with infinite scroll on course listing pages for a smoother browsing experience.

Details

• Implement intersection observer-based infinite scroll
• Add loading spinner at bottom during fetch
• Handle empty and error states gracefully
• Implement scroll position restoration
• Add virtual list optimization for large datasets

Labels

area: frontend, frontend, performance, enhancement, priority: medium

[ifygreg01-best]

I would love to work on this issue please assign me

[grantfox-oss]

🦊 GrantFox — @ifygreg01-best has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #196)
2. Your PR will be reviewed by the Epondia maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@ifygreg01-best's PR #220 was approved and merged by @jobbykings.

🏆 @ifygreg01-best: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (416 total points). Track your full progress on GrantFox.

👏 Great work, @ifygreg01-best! Keep contributing to Epondia.