feat: implement Topic Feed UI/UX enhancement

[Faromzy]

feat: Topic Feed UI/UX Enhancement

Summary

Implements the Topic Feed feature for the /topics/[slug] route, providing users
with a dedicated page to browse and discover posts within a specific topic.

Changes

• src/utils/socialUtils.ts — Added Topic and TopicPost types

• src/hooks/useTopicFeed.ts — New hook handling data fetching, pagination
  (cursor-based), and sort state (latest, popular, oldest)

• src/components/social/TopicFeed.tsx — New client component with:

  • Topic header (name, description, post/follower counts)
  • Sort controls (Latest / Popular / Oldest)
  • Infinite scroll via IntersectionObserver
  • Skeleton loading states
  • Empty and error states
  • Accessible markup (role, aria-*, , )

• src/app/topics/[slug]/page.tsx — Server component with dynamic
  generateMetadata

What was tested

• Component renders skeleton on initial load
• Sort change resets and refetches posts
• Infinite scroll sentinel triggers loadMore
• Error and empty states display correctly

Notes

• Uses existing apiClient from @/lib/api — no new dependencies
• Follows project conventions: Tailwind CSS, lucide-react icons, dark mode
  support

Closes #527

[drips-wave]

@Faromzy Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits