feat: add version info endpoint and display in UI

public/js/main.js

@@ -2757,6 +2757,27 @@ async function loadSettings() {
   }
 }
 
+/**
+ * Load and display version info
+ */
+async function loadVersionInfo() {
+  try {
+    const response = await fetch('/api/version');
+    if (!response.ok) return;
+    
+    const versionData = await response.json();
+    const versionEl = document.getElementById('versionInfo');
+    
+    if (versionEl && versionData.commit) {
+      const shortHash = versionData.commit.substring(0, 7);
+      versionEl.textContent = shortHash !== 'dev' ? shortHash : 'dev';
+      versionEl.title = `Commit: ${versionData.commit}\nBuild: ${versionData.buildDate}`;
+    }
+  } catch (error) {
+    console.log('Could not load version info:', error);
+  }
+}
+
 /**
  * Handle vacation days input change
  */
@@ -3781,6 +3802,7 @@ document.addEventListener('DOMContentLoaded', async () => {
   initializeFlatpickr();
   initializeEventListeners();
   await loadSettings(); // Load saved settings first
+  await loadVersionInfo(); // Load version info
   checkRunningTimer(); // Check if timer was running
   loadMonthlyView(); // Load monthly view by default
 });