refactor i czytanie

nav.js

@@ -1,18 +1,17 @@
-// Shared hamburger menu toggle
+// Back-to-hub button with active-task confirmation
 (function () {
   document.addEventListener('DOMContentLoaded', () => {
-    const btn = document.getElementById('hamburger-btn')
-    const menu = document.getElementById('hamburger-menu')
-    if (!btn || !menu) return
-    btn.addEventListener('click', (e) => {
-      e.stopPropagation()
-      menu.classList.toggle('open')
-    })
-    document.addEventListener('click', () => menu.classList.remove('open'))
-    // mark active link
-    const current = location.pathname.split('/').pop() || 'index.html'
-    menu.querySelectorAll('a').forEach(a => {
-      if (a.getAttribute('href') === current) a.classList.add('active')
+    const backBtn = document.getElementById('back-to-hub')
+    if (!backBtn) return
+
+    backBtn.addEventListener('click', (e) => {
+      const playScreen = document.getElementById('play-screen')
+      const taskActive = playScreen && !playScreen.classList.contains('hidden')
+      if (taskActive) {
+        e.preventDefault()
+        const ok = confirm('Masz aktywne zadanie. Czy na pewno chcesz wyjść do menu?')
+        if (ok) window.location.href = backBtn.getAttribute('href')
+      }
     })
   })
 })()