odstranenie priemernej dlzky hry zo statistik

frontend/src/pages/admin/AdminStats.tsx

@@ -19,7 +19,6 @@ interface DailyStats {
   players_per_day: Record<string, number>;
   finished_bot_games: number;
   finished_human_games: number;
-  avg_game_duration_minutes: number | null;
   total_players: number;
   unconfirmed_players: number;
   peak_hours: Record<string, number>;
@@ -159,10 +158,6 @@ export default function AdminStats() {
         <SummaryCard label="Nedokončené registrácie" value={String(data.unconfirmed_players)} />
         <SummaryCard label="Dokončené hry s ľuďmi" value={String(data.finished_human_games)} />
         <SummaryCard label="Dokončené hry s botmi" value={String(data.finished_bot_games)} />
-        <SummaryCard
-          label="Priem. dĺžka hry"
-          value={data.avg_game_duration_minutes != null ? `${Math.round(data.avg_game_duration_minutes)} min` : '—'}
-        />
       </div>
 
       <div className={`grid gap-4 ${desktop ? 'grid-cols-2' : 'grid-cols-1'}`}>