fix(mobile-app): correct leaderboard status API path

The API base URL already includes /api/v1, so the path should be
/leaderboard/status instead of /leaderboard-service/api/v1/leaderboard/status

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mobile-app/lib/core/services/leaderboard_service.dart

@@ -68,7 +68,7 @@ class LeaderboardService {
 
     try {
       final response = await _apiClient.get(
-        '/leaderboard-service/api/v1/leaderboard/status',
+        '/leaderboard/status',
       );
 
       if (response.data != null && response.data['data'] != null) {