Fix TypeError: Replace isValidPosition with isPlayable method

- Fixed critical bug where isBoardFull() was calling non-existent isValidPosition method
- Replaced with correct isPlayable() method from working game code
- Background AI game should now work properly without crashing
- Also improved QR code text visibility and added auto-restart functionality

presentation_no_iframe.html

@@ -526,7 +526,7 @@
                 </div>
             </div>
             
-            <p style="font-size: 1.1em; color: #666;">Play on your device or scan the QR code for mobile access</p>
+            <p style="font-size: 1.8em; color: #fff; margin-top: 20px; font-weight: bold;">Play on your device or scan the QR code for mobile access</p>
         </div>
     </div>
 
@@ -1112,6 +1112,17 @@
                         return;
                     }
                 }
+                
+                // Check for stalemate (board full or no moves possible)
+                if (this.isBoardFull() || this.noMovesRemaining()) {
+                    console.log('🔄 Game stalemate detected, restarting...');
+                    setTimeout(() => {
+                        this.resetGame();
+                        if (this.playerTypes[this.currentPlayer] === 'ai') {
+                            setTimeout(() => this.makeAIMove(), this.aiMoveDelay);
+                        }
+                    }, 3000);
+                }
             }
 
             checkFiveInRow(player) {
@@ -1132,6 +1143,29 @@
                 return false;
             }
             
+            isBoardFull() {
+                for (let r = 0; r < 13; r++) {
+                    for (let c = 0; c < 13; c++) {
+                        if (this.isPlayable(r, c) && this.board[r][c] === null) {
+                            return false;
+                        }
+                    }
+                }
+                return true;
+            }
+            
+            noMovesRemaining() {
+                // Check if both players have no pieces left to play
+                for (let player = 1; player <= 2; player++) {
+                    const inventory = this.inventory[player];
+                    const totalPieces = inventory.fire + inventory.water + inventory.earth + inventory.air + inventory.love;
+                    if (totalPieces > 0) {
+                        return false;
+                    }
+                }
+                return true;
+            }
+            
             checkLineFromPosition(startR, startC, direction, player, length) {
                 let firstElement = null;
                 
@@ -1221,9 +1255,15 @@
                 }
                 
                 // Auto-restart for presentation
+                console.log(`🎯 Game Over! Player ${winner} won. Restarting in 4 seconds...`);
                 setTimeout(() => {
+                    console.log('🔄 Restarting game...');
                     this.resetGame();
-                }, 2000);
+                    // Ensure AI starts playing again
+                    if (this.playerTypes[this.currentPlayer] === 'ai') {
+                        setTimeout(() => this.makeAIMove(), this.aiMoveDelay);
+                    }
+                }, 4000);
             }
             
             resetGame() {