fix: remove isStalemate API call (doubled request count), reduce max to 60

The isStalemate() called the Stockfish API on every move just to check
if the opponent had legal moves — doubling API calls from 80 to 160 per
game. Now relies on the API returning no best_move as game-over signal.
Differentiates checkmate vs stalemate by eval magnitude.

Also reduced max moves from 80 to 60 — bot games at these levels
should resolve well before that.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

modules/tournaments/services/BotGamePlayerService.php

@@ -76,7 +76,7 @@ class BotGamePlayerService
         $lastEval = 0.0;
         $result = null;
         $resultReason = null;
-        $maxMoves = 80;
+        $maxMoves = 60;
         $sanMoves = [];
 
         while ($moveCount < $maxMoves) {
@@ -89,12 +89,14 @@ class BotGamePlayerService
             ]);
 
             if ($response['status'] !== 200 || empty($response['body']['best_move'])) {
-                if ($sideToMove === 'w') {
-                    $result = 'black_wins';
+                $eval = abs($response['body']['evaluation'] ?? 0);
+                if ($eval > 50) {
+                    $result = ($sideToMove === 'w') ? 'black_wins' : 'white_wins';
+                    $resultReason = 'checkmate';
                 } else {
-                    $result = 'white_wins';
+                    $result = 'stalemate';
+                    $resultReason = 'stalemate';
                 }
-                $resultReason = 'checkmate';
                 break;
             }
 
@@ -142,11 +144,6 @@ class BotGamePlayerService
                 break;
             }
 
-            if (self::isStalemate($newFen)) {
-                $result = 'stalemate';
-                $resultReason = 'stalemate';
-                break;
-            }
         }
 
         if ($result === null && $moveCount >= $maxMoves) {
@@ -188,15 +185,6 @@ class BotGamePlayerService
         return $parts[1] ?? 'w';
     }
 
-    private static function isStalemate(string $fen): bool
-    {
-        $response = ApiProxy::stockfish('POST', '/api/chess/move', [
-            'fen' => $fen,
-            'bot_id' => 'grandmaster',
-        ]);
-        return $response['status'] !== 200 || empty($response['body']['best_move']);
-    }
-
     private static function uciToSan(string $fen, string $uciMove): string
     {
         $from = substr($uciMove, 0, 2);