Fix quantity input +/- buttons decrementing under screen readers

QuantityInput.onButtonClick used event.target.name to determine which
button was pressed. When activated via screen reader/keyboard, the
event target resolves to the visually-hidden accessible-name span
inside the button (which has no name attribute) rather than the
button itself, so the plus button incorrectly fell through to
stepDown(). Mouse clicks were unaffected since they hit-test to the
button directly.

Use event.currentTarget.name instead, matching the pattern already
used in the slider's onButtonClick in the same file.

Fixes #3972

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EFhzTdXdDnPmBJzysuzKuD

Author: 2 people

assets/global.js

@@ -246,7 +246,7 @@ class QuantityInput extends HTMLElement {
     event.preventDefault();
     const previousValue = this.input.value;
 
-    if (event.target.name === 'plus') {
+    if (event.currentTarget.name === 'plus') {
       if (parseInt(this.input.dataset.min) > parseInt(this.input.step) && this.input.value == 0) {
         this.input.value = this.input.dataset.min;
       } else {
@@ -258,7 +258,7 @@ class QuantityInput extends HTMLElement {
 
     if (previousValue !== this.input.value) this.input.dispatchEvent(this.changeEvent);
 
-    if (this.input.dataset.min === previousValue && event.target.name === 'minus') {
+    if (this.input.dataset.min === previousValue && event.currentTarget.name === 'minus') {
       this.input.value = parseInt(this.input.min);
     }
   }