fix: filter non-touch pointer events in touchscreen.html to match upstream

Chrome 147 fires additional non-touch pointer events that were being recorded
in allEvents, causing ShouldWorkWithTwoTouches to fail. Sync with upstream
which added `if (event.pointerType !== 'touch') return` guard.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: kblok

lib/PuppeteerSharp.TestServer/wwwroot/input/touchscreen.html

@@ -49,6 +49,9 @@
         globalThis.addEventListener(
             name,
             (event) => {
+                if (event.pointerType !== 'touch') {
+                    return;
+                }
                 allEvents.push({
                     type: name,
                     x: event.x,