Add React + Vite port of the logo generator

Full React port sharing src/logo.js core (shadow geometry, CSS
output, defaults, font list). App.jsx holds the entire state in a
single useState object; controlled inputs drive the live render and
generated CSS. Keeps the accessibility markup (labels, aria,
<details>/<summary>, focus rings) from the html/vanilla versions;
reset restores defaults via the form's onReset.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

vite.config.js

@@ -0,0 +1,6 @@
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+
+export default defineConfig({
+  plugins: [react()],
+});