fix: competition chart data sync and display issues

- Add real-time data point to equity history API for chart/leaderboard consistency
- Fix chart legend showing 0% by finding each trader's last available data point
- Use consistent timestamp for all real-time data points in batch requests
- Increase chart trader limit from 5 to 10
- Remove Mini Stats Bar trader limit

web/src/components/CompetitionPage.tsx

@@ -210,7 +210,7 @@ export function CompetitionPage() {
               {t('realTimePnL', language)}
             </div>
           </div>
-          <ComparisonChart traders={sortedTraders.slice(0, 5)} />
+          <ComparisonChart traders={sortedTraders.slice(0, 10)} />
         </div>
 
         {/* Right: Leaderboard */}