feat: scaffold Svelte app with shared types and scale calculation

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

vite.config.ts

@@ -0,0 +1,15 @@
+import { defineConfig } from 'vitest/config';
+import { svelte } from '@sveltejs/vite-plugin-svelte';
+
+export default defineConfig({
+  plugins: [svelte()],
+  // Rune modules must compile for the browser runtime under Vitest too.
+  resolve: process.env.VITEST ? { conditions: ['browser'] } : undefined,
+  build: { chunkSizeWarningLimit: 12000 },
+  test: {
+    environment: 'node',
+    include: ['tests/**/*.test.ts'],
+    testTimeout: 30000,
+    hookTimeout: 60000,
+  },
+});