feat: initial scaffold with Event Management, Participant Management, and Budget Management

- Express backend with JWT auth, PostgreSQL, full CRUD APIs
- React + Vite + TailwindCSS frontend with RTL Hebrew UI
- Event Creation & Management (create/edit/delete/list events)
- Participant Management (add/edit/delete/status tracking per event)
- Budget Management (income/expense tracking with balance summary)
- Docker Compose setup with PostgreSQL
- /health endpoint with commit-id and DB status

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

client/src/lib/auth.js

@@ -0,0 +1,15 @@
+export function setToken(token) {
+  localStorage.setItem('token', token);
+}
+
+export function getToken() {
+  return localStorage.getItem('token');
+}
+
+export function removeToken() {
+  localStorage.removeItem('token');
+}
+
+export function isLoggedIn() {
+  return !!getToken();
+}