tweak: reduce swipe-up overlay speed from 2.5x to 1.5x for smoother feel

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

src/main.js

@@ -264,7 +264,7 @@ window.addEventListener('load', () => {
       if(npOverlay) {
         npOverlay.style.transition = 'none';
         // Overlay tracks finger with no cap: 2.5× speed so ~360px drag = fully open.
-        npOverlay.style.transform = `translateY(${Math.max(0, window.innerHeight - dy * 2.5)}px)`;
+        npOverlay.style.transform = `translateY(${Math.max(0, window.innerHeight - dy * 1.5)}px)`;
       }
     }, {passive:true});