fix: resolve React key duplicates and NaN in profile page

- Fix NaN error in impact score calculation by handling undefined reportCount/eventCount
- Fix duplicate React keys in activity timeline by using unique composite keys
- Add reportCount and eventCount to backend profile response to match frontend expectations
- Keep stats object for backward compatibility

Fixes:
- 'Received NaN for children attribute' warning
- 'Encountered two children with the same key' errors

server/src/services/userService.ts

@@ -98,6 +98,8 @@ export class UserService {
 
     return {
       ...user,
+      reportCount: user._count.reports,
+      eventCount: user._count.eventRegistrations,
       stats: {
         reportsSubmitted: user._count.reports,
         eventsAttended: user._count.eventRegistrations,