Replace hero mockup with auto-rotating screenshot carousel

- Swap static dashboard card for 3-slide image carousel in hero section
- Slides auto-advance every 4.5s, pause on hover, support manual prev/next and dot navigation
- Add carousel CSS with fade transition, dot indicators, and glow border treatment
- Add carousel JS with goTo/prev/next/auto-rotate logic
- Images expected at img/screenshot-dashboard.png, img/screenshot-cashflow.png, img/screenshot-capital.png

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

app.js

@@ -20,6 +20,52 @@
   if (signupEl) signupEl.textContent = text;
 })();
 
+// ── Screenshot Carousel ──────────────────────────────────
+(function initCarousel() {
+  const carousel = document.getElementById('screenshotCarousel');
+  if (!carousel) return;
+
+  const slides = carousel.querySelectorAll('.carousel-slide');
+  const dots   = carousel.querySelectorAll('.carousel-dot');
+  let current  = 0;
+  let timer;
+
+  function goTo(index) {
+    slides[current].classList.remove('active');
+    dots[current].classList.remove('active');
+    current = (index + slides.length) % slides.length;
+    slides[current].classList.add('active');
+    dots[current].classList.add('active');
+  }
+
+  function next() { goTo(current + 1); }
+  function prev() { goTo(current - 1); }
+
+  function startAuto() {
+    timer = setInterval(next, 4500);
+  }
+  function resetAuto() {
+    clearInterval(timer);
+    startAuto();
+  }
+
+  carousel.querySelector('.carousel-next').addEventListener('click', () => { next(); resetAuto(); });
+  carousel.querySelector('.carousel-prev').addEventListener('click', () => { prev(); resetAuto(); });
+
+  dots.forEach(dot => {
+    dot.addEventListener('click', () => {
+      goTo(parseInt(dot.dataset.index, 10));
+      resetAuto();
+    });
+  });
+
+  // Pause on hover
+  carousel.addEventListener('mouseenter', () => clearInterval(timer));
+  carousel.addEventListener('mouseleave', startAuto);
+
+  startAuto();
+})();
+
 // ── Form Handler ─────────────────────────────────────────
 document.addEventListener('DOMContentLoaded', () => {
   const form       = document.getElementById('signupForm');