feat: serve demo/ folder as static route at /demo

Adds express.static middleware for the demo/ directory mounted at /demo,
placed before the SPA catch-all so /demo/index.html resolves to the
standalone stakeholder demo page instead of the React app.

server.js

@@ -11,6 +11,11 @@ app.use(cors());
 app.use(express.json());
 app.use(express.static(path.join(__dirname, 'client', 'dist')));
 
+// ── Demo static route ─────────────────────────────────────────────────────────
+// Serves the standalone stakeholder demo page at /demo/index.html
+// Must be registered before the SPA catch-all below.
+app.use('/demo', express.static(path.join(__dirname, 'demo')));
+
 // ── Audit helper ─────────────────────────────────────────────────────────────
 function audit(action, entityType, entityId, performedBy, details) {
   try {