fix: Add route for /demo.html page

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/encryptid/server.ts

@@ -431,6 +431,7 @@ async function generateSessionToken(userId: string, username: string): Promise<s
 // ============================================================================
 
 // Serve demo page and static assets
+app.get('/demo.html', serveStatic({ path: './src/encryptid/demo.html' }));
 app.use('/demo/*', serveStatic({ root: './src/encryptid/' }));
 app.use('/static/*', serveStatic({ root: './public/' }));