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>

vite.config.ts

@@ -1,12 +1,12 @@
 
 import { defineConfig } from 'vite'
-import react from '@vitejs/plugin-react'
+import preact from '@preact/preset-vite'
 import tailwindcss from '@tailwindcss/vite'
 import { resolve } from 'path'
 
 // https://vitejs.dev/config/
 export default defineConfig({
-  plugins: [react(), tailwindcss()],
+  plugins: [preact(), tailwindcss()],
   build: {
     rollupOptions: {
       input: {