[Frontend] Improve loading for events page

[dyzhuu]

🎯 Acceptance Criteria

• Read up on nextjs loading.tsx and also Suspense streaming
• Create a loading.tsx for the events page
• Create a Fallback component for the event cards
• Stream the cards in with suspense boundaries.

---

📊 Definition of Done (DoD)

• Acceptance criteria met
• Agreed tests written
• Agreed documentation in GitHub wiki
• PR reviewed

---

🔗 Dependencies

---

📚 Additional Context