fix: domino drag-drop re-evaluates hit on touchend

When touchend fires without updating pointer coordinates (common in
headless environments and some mobile browsers), the proxy position
is used to re-check endpoint hit test before deciding placement.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/js/modules/domino/components/drag.js

@@ -117,6 +117,20 @@ export class DominoDrag {
     document.removeEventListener('pointercancel', this._onUp);
     document.removeEventListener('touchend', this._onUp);
 
+    // Re-check hit from proxy position (touchend may not update pointer coords)
+    if (!this.nearEnd && this.proxyEl) {
+      const left = parseInt(this.proxyEl.style.left) || 0;
+      const top = parseInt(this.proxyEl.style.top) || 0;
+      const hit = this.board.hitTestEndpoints(left + 20, top + 35);
+      if (hit) {
+        const tileMatches = this.tile.left === hit.value || this.tile.right === hit.value;
+        if (tileMatches) {
+          this.nearEnd = hit.end;
+          this.isValid = true;
+        }
+      }
+    }
+
     this.board.clearGhost();
 
     if (this.nearEnd && this.isValid) {