Fix CSP violations and ignoreAvailable reference error

- Add .hidden utility class to style.css for CSP compliance
- Replace all inline style='display: none' with class='hidden' in HTML
- Update all UI modules to use classList.add/remove instead of style.display
- Fix ignoreAvailable reference error in history.js (use state.ignoreAvailable)
- Rebuild client bundle with vite

client/src/ui/tabs.js

@@ -26,20 +26,20 @@ export function initTabs() {
 export function activateTab(tab) {
   const downloadsTab = document.getElementById('downloads-tab');
   const historyTab = document.getElementById('history-tab');
-  const downloadsSection = document.getElementById('downloads-section');
-  const historySection = document.getElementById('history-section');
+  const downloadsSection = document.getElementById('tab-downloads');
+  const historySection = document.getElementById('tab-history');
   
   if (tab === 'downloads') {
     downloadsTab.classList.add('active');
     historyTab.classList.remove('active');
-    downloadsSection.style.display = 'block';
-    historySection.style.display = 'none';
+    downloadsSection.classList.remove('hidden');
+    historySection.classList.add('hidden');
     saveActiveTab('downloads');
   } else if (tab === 'history') {
     historyTab.classList.add('active');
     downloadsTab.classList.remove('active');
-    historySection.style.display = 'block';
-    downloadsSection.style.display = 'none';
+    historySection.classList.remove('hidden');
+    downloadsSection.classList.add('hidden');
     saveActiveTab('history');
     loadHistory();
   }