Statistiky: dokoncene hry rozdelene na s ludmi / s botmi

Karta "Dokoncene hry" (%) nahradena dvomi poctami dokoncenych hier
podla toho, ci na niektorom sedadle sedel bot (username "bot:...").
Zaroven oprava serializacie avg_game_duration_minutes -- Postgres
vracia z func.avg Decimal, ktory json.dumps nevie serializovat (500
na /api/admin/stats).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/pages/admin/AdminStats.tsx

@@ -17,7 +17,8 @@ import PageviewsChart from './PageviewsChart';
 interface DailyStats {
   games_per_day: Record<string, number>;
   players_per_day: Record<string, number>;
-  completion_rate: number | null;
+  finished_bot_games: number;
+  finished_human_games: number;
   avg_game_duration_minutes: number | null;
   total_players: number;
   unconfirmed_players: number;
@@ -157,10 +158,8 @@ export default function AdminStats() {
       <div className={`flex gap-3 ${desktop ? '' : 'flex-wrap'}`}>
         <SummaryCard label="Hráči celkom" value={String(data.total_players)} />
         <SummaryCard label="Nedokončené registrácie" value={String(data.unconfirmed_players)} />
-        <SummaryCard
-          label="Dokončené hry"
-          value={data.completion_rate != null ? `${Math.round(data.completion_rate * 100)}%` : '—'}
-        />
+        <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` : '—'}