Harden virtual joystick pointer capture

src/game.js

@@ -809,7 +809,11 @@
 
   if (moveStick) {
     moveStick.addEventListener("pointerdown", (event) => {
-      moveStick.setPointerCapture?.(event.pointerId);
+      try {
+        moveStick.setPointerCapture?.(event.pointerId);
+      } catch {
+        // Synthetic or interrupted pointer events may not be capturable.
+      }
       updateStick(event);
     });
     moveStick.addEventListener("pointermove", updateStick);