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>

package.json

@@ -0,0 +1,24 @@
+{
+  "name": "demo-ecmascript-react",
+  "version": "1.0.0",
+  "description": "LIBRETECH logo generator — React + Vite",
+  "repository": {
+    "type": "git",
+    "url": "ssh://tengo@git.librete.ch:41240/public/demo-ecmascript.git"
+  },
+  "license": "WTFPL",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0"
+  },
+  "devDependencies": {
+    "@vitejs/plugin-react": "^4.3.4",
+    "vite": "^6.0.0"
+  }
+}