feat: Implement RecentActivity feed on dashboard

[derekliutao-cmd]

Summary

Closes #2

Implements the RecentActivity component on the dashboard as specified in the bounty issue.

Changes

src/types/index.ts — Added NotificationType and Notification interfaces.

src/components/dashboard/recent-activity.tsx — Full implementation:

• ✅ Fetches notifications via React Query (useQuery) keyed on connected wallet address
• ✅ Scrollable feed with 4 distinct activity type icons (💰 contribution, 🏧 loan, 🗳️ vote, 📤 distribution) using lucide-react
• ✅ Relative timestamps via date-fns formatDistanceToNow
• ✅ Subtle separator lines between items
• ✅ "Connect your wallet to see activity" state when no wallet connected
• ✅ "No recent activity" empty state
• ✅ "Mark all read" button (calls PATCH /api/notifications/:id/read) shown only when unread items exist
• ✅ Unread indicators (blue dot + subtle background highlight)
• ✅ Mock data included with clear // TODO: connect to API comments for backend integration
• ✅ No TypeScript errors (valid TS, correct imports)

Implementation Notes

• Uses existing project dependencies only (@tanstack/react-query, date-fns, lucide-react, axios)
• Follows existing codebase patterns (same styling, component structure, hook usage)
• The markAllRead mutation invalidates the query cache for automatic refresh
• Loading and error states handled gracefully

[derekliutao-cmd]

Hi @Mona-i! I noticed PR #23 (merged) also touched the RecentActivity component. My PR #30 provides a standalone, focused implementation with:

• React Query for data fetching with 60s auto-refresh
• Separate markAllRead mutation with cache invalidation
• Proper loading/empty states
• Mock data with clear TODO comments for API integration

Happy to adjust if there's any overlap concern. Thanks for reviewing!