feat: add command palette, accessibility, scroll animations, demo workspace, and keyboard navigation

- COMP-139: Command palette for quick navigation
- COMP-140: Accessibility improvements
- COMP-141: Scroll animations with animate-on-scroll component
- COMP-143: Demo workspace with seed data and demo banner
- COMP-145: Keyboard navigation and shortcuts help

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-Claude)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

apps/web/src/components/animate-on-scroll.tsx

@@ -0,0 +1,60 @@
+"use client";
+
+import { useEffect, useRef, ReactNode } from "react";
+
+interface AnimateOnScrollProps {
+  children: ReactNode;
+  className?: string;
+  delay?: number;
+  threshold?: number;
+}
+
+export function AnimateOnScroll({
+  children,
+  className = "",
+  delay = 0,
+  threshold = 0.15,
+}: AnimateOnScrollProps) {
+  const ref = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    const el = ref.current;
+    if (!el) return;
+
+    const prefersReduced = window.matchMedia(
+      "(prefers-reduced-motion: reduce)"
+    ).matches;
+
+    if (prefersReduced) {
+      el.setAttribute("data-animate", "visible");
+      return;
+    }
+
+    const observer = new IntersectionObserver(
+      (entries) => {
+        for (const entry of entries) {
+          if (entry.isIntersecting) {
+            entry.target.setAttribute("data-animate", "visible");
+            observer.unobserve(entry.target);
+          }
+        }
+      },
+      { threshold }
+    );
+
+    observer.observe(el);
+
+    return () => observer.disconnect();
+  }, [threshold]);
+
+  return (
+    <div
+      ref={ref}
+      data-animate="hidden"
+      className={className}
+      style={{ animationDelay: delay ? `${delay}ms` : undefined }}
+    >
+      {children}
+    </div>
+  );
+}