migrate to Preact and add iOS-feel animations

- Replace React 19 with Preact via @preact/preset-vite (zero component changes needed — Vite aliases react → preact/compat at build time)
- Add custom iOS easing curves (ease-ios, ease-spring) via Tailwind @theme
- Update all transitions to use iOS-standard 200ms durations and spring/decel easing
- Add active:scale press feedback on tiles, buttons, and toggles
- Toggle knob now uses spring easing for a satisfying snap

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

components/layout/EditButton.tsx

@@ -10,7 +10,7 @@ const EditButton: React.FC<EditButtonProps> = ({ isEditing, onClick }) => {
     <div className="absolute top-4 left-4">
       <button
         onClick={onClick}
-        className="bg-black/25 backdrop-blur-md border border-white/10 rounded-xl p-3 text-white flex items-center gap-2 hover:bg-white/25 transition-colors"
+        className="bg-black/25 backdrop-blur-md border border-white/10 rounded-xl p-3 text-white flex items-center gap-2 hover:bg-white/25 active:scale-90 transition-all duration-200 ease-ios"
         style={{ fontSize: '12px' }}
       >
         <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" className="bi bi-pencil" viewBox="0 0 16 16">