Fix jarring smooth scroll with sine-based easing

- Replace easeInOutQuad with easeInOutSine for natural motion
- Add user interruption handling (cancel on wheel/touch/keyboard)
- Add accessibility support for prefers-reduced-motion
- Optimize duration from 1800ms to 1200ms
- Add proper cleanup of event listeners and animation frames
- Update all component references to use new duration

The sine-based easing creates smooth, consistent motion throughout
the entire scroll duration without jarring speed changes.

apps/website/components/AppNavbar.vue

@@ -65,11 +65,11 @@ const handleSmoothScroll = (event: Event, href: string) => {
   }
 
   event.preventDefault()
-  scrollToElement(href, 1800) // 1.8 seconds for smoother scrolling
+  scrollToElement(href, 1200) // Smooth scrolling with sine easing
 }
 
 const scrollToTop = () => {
-  smoothScrollToTop(1800) // 1.8 seconds for smoother scrolling
+  smoothScrollToTop(1200) // Smooth scrolling with sine easing
 }
 
 onMounted(() => {

apps/website/components/HeroSection.vue

@@ -101,11 +101,11 @@ const handlePhoneClick = () => {
 }
 
 const handleServicesClick = () => {
-  scrollToElement('#services', 1800) // 1.8 seconds for smoother scrolling
+  scrollToElement('#services', 1200) // Smooth scrolling with sine easing
 }
 
 const handleScrollToExplore = () => {
-  scrollToElement('#services', 1800) // Scroll to services section
+  scrollToElement('#services', 1200) // Smooth scroll to services section
 }
 
 const handleVideoVisibility = () => {
@@ -136,7 +136,7 @@ const initSmoothScroll = () => {
       if (!href) {
         return
       }
-      scrollToElement(href, 1800) // 1.8 seconds for smoother scrolling
+      scrollToElement(href, 1200) // Smooth scrolling with sine easing
     })
   })
 }

apps/website/composables/useSmoothScroll.ts

@@ -1,8 +1,40 @@
 export const useSmoothScroll = () => {
-  const smoothScrollTo = (target: number | Element, duration: number = 1800) => {
+  let animationFrameId: number | null = null
+
+  // Cancel any ongoing scroll animation
+  const cancelScroll = () => {
+    if (animationFrameId) {
+      cancelAnimationFrame(animationFrameId)
+      animationFrameId = null
+    }
+    // Clean up event listeners
+    window.removeEventListener('wheel', cancelScroll)
+    window.removeEventListener('touchstart', cancelScroll)
+    window.removeEventListener('keydown', cancelScroll)
+  }
+
+  // Smooth sine-based easing function for natural motion
+  const easeInOutSine = (t: number): number => {
+    return -(Math.cos(Math.PI * t) - 1) / 2
+  }
+
+  const smoothScrollTo = (target: number | Element, duration: number = 1200) => {
+    // Check for reduced motion preference
+    const prefersReducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)').matches
+
     const targetPosition = typeof target === 'number'
       ? target
       : target.getBoundingClientRect().top + window.pageYOffset
+
+    if (prefersReducedMotion) {
+      // Instant scroll for accessibility
+      window.scrollTo(0, targetPosition)
+      return
+    }
+
+    // Cancel any previously running scroll animation
+    cancelScroll()
+
     const startPosition = window.pageYOffset
     const distance = targetPosition - startPosition
     let startTime: number | null = null
@@ -11,32 +43,33 @@ export const useSmoothScroll = () => {
       if (startTime === null) startTime = currentTime
       const timeElapsed = currentTime - startTime
       const progress = Math.min(timeElapsed / duration, 1)
+      const easedProgress = easeInOutSine(progress)
 
-      // Easing function for smoother, more consistent motion
-      const easeInOutQuad = (t: number) => {
-        return t < 0.5
-          ? 2 * t * t
-          : 1 - Math.pow(-2 * t + 2, 2) / 2
-      }
-
-      window.scrollTo(0, startPosition + distance * easeInOutQuad(progress))
+      window.scrollTo(0, startPosition + distance * easedProgress)
 
       if (progress < 1) {
-        requestAnimationFrame(animation)
+        animationFrameId = requestAnimationFrame(animation)
+      } else {
+        cancelScroll() // Clean up when animation completes
       }
     }
 
-    requestAnimationFrame(animation)
+    // Add listeners to detect user interruption
+    window.addEventListener('wheel', cancelScroll, { passive: true })
+    window.addEventListener('touchstart', cancelScroll, { passive: true })
+    window.addEventListener('keydown', cancelScroll, { once: true })
+
+    animationFrameId = requestAnimationFrame(animation)
   }
 
-  const scrollToElement = (selector: string, duration: number = 1800) => {
+  const scrollToElement = (selector: string, duration: number = 1200) => {
     const element = document.querySelector(selector)
     if (element) {
       smoothScrollTo(element, duration)
     }
   }
 
-  const scrollToTop = (duration: number = 1800) => {
+  const scrollToTop = (duration: number = 1200) => {
     smoothScrollTo(0, duration)
   }