Port logo generator to vanilla JS + Vite

Restructure the single-file demo into a Vite project:

- src/logo.js: framework-agnostic core (shadow-layer geometry,
  inline text-shadow, generated CSS snippet, defaults, font list)
- src/main.js: DOM wiring (state read, live render, copy, native reset)
- src/style.css, index.html: markup + styles with the accessibility
  fixes (labels, aria, <details>/<summary>, <form> reset, focus rings)

The original single-file version lives on the 'html' branch.

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

package.json

@@ -0,0 +1,19 @@
+{
+  "name": "demo-ecmascript",
+  "version": "1.0.0",
+  "description": "LIBRETECH logo generator — vanilla JS + 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"
+  },
+  "devDependencies": {
+    "vite": "^6.0.0"
+  }
+}