Initial commit: Deklinationstrainer German declension trainer

Vite + React app for daily German declension practice with
localStorage-backed progress. Includes Coolify deploy instructions.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/main.jsx

@@ -0,0 +1,9 @@
+import { StrictMode } from 'react'
+import { createRoot } from 'react-dom/client'
+import App from './App.jsx'
+
+createRoot(document.getElementById('root')).render(
+  <StrictMode>
+    <App />
+  </StrictMode>,
+)