interactivity was broken

src/main.ts

@@ -266,21 +266,30 @@ class BitfielderApp {
         
         // Touch tracking
         window.addEventListener('touchstart', (e) => {
-            e.preventDefault();
+            // Only prevent default on canvas area for shader interaction
+            if (e.target === this.canvas) {
+                e.preventDefault();
+            }
             this.touchCount = e.touches.length;
             this.updateTouchPositions(e.touches);
             this.initializePinchGesture(e.touches);
         });
         
         window.addEventListener('touchmove', (e) => {
-            e.preventDefault();
+            // Only prevent default on canvas area to allow UI scrolling
+            if (e.target === this.canvas) {
+                e.preventDefault();
+            }
             this.touchCount = e.touches.length;
             this.updateTouchPositions(e.touches);
             this.updatePinchGesture(e.touches);
         });
         
         window.addEventListener('touchend', (e) => {
-            e.preventDefault();
+            // Only prevent default on canvas area
+            if (e.target === this.canvas) {
+                e.preventDefault();
+            }
             this.touchCount = e.touches.length;
             if (this.touchCount === 0) {
                 this.touch0X = this.touch0Y = this.touch1X = this.touch1Y = 0;