Add footer with mailto link, version and build date

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

vite.config.ts

@@ -1,6 +1,13 @@
 import { sveltekit } from '@sveltejs/kit/vite';
 import { defineConfig } from 'vite';
+import { readFileSync } from 'fs';
+
+const pkg = JSON.parse(readFileSync('./package.json', 'utf-8'));
 
 export default defineConfig({
-	plugins: [sveltekit()]
+	plugins: [sveltekit()],
+	define: {
+		__APP_VERSION__: JSON.stringify(pkg.version),
+		__BUILD_DATE__: JSON.stringify(new Date().toLocaleDateString('de-DE')),
+	}
 });