feat: scaffold Svelte app with shared types and scale calculation

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

svelte.config.js

@@ -0,0 +1,3 @@
+import { vitePreprocess } from '@sveltejs/vite-plugin-svelte';
+
+export default { preprocess: vitePreprocess({ script: true }) };