feat: project scaffold with tabs, styles and package.json

js/app.js

@@ -0,0 +1,25 @@
+import { renderEmployees } from './employees.js';
+import { renderCalendar } from './calendar.js';
+import { renderDataTab } from './history.js';
+
+// Shared mutable state — imported by all other modules
+export const state = {
+  employees: [],
+  calendar: { holidays: [], companyClosures: [] },
+  history: []
+};
+
+// Tab switching
+document.querySelectorAll('.tab-btn').forEach(btn => {
+  btn.addEventListener('click', () => {
+    const tab = btn.dataset.tab;
+    document.querySelectorAll('.tab-btn').forEach(b => b.classList.remove('active'));
+    document.querySelectorAll('.tab-content').forEach(s => s.classList.add('hidden'));
+    btn.classList.add('active');
+    document.getElementById('tab-' + tab).classList.remove('hidden');
+    if (tab === 'planning') renderCalendar();
+    if (tab === 'data') renderDataTab();
+  });
+});
+
+renderEmployees();