fix: remove 7 unused variables in widgets and Homepage components

Cleaned up unused imports, parameters, and variables:
- DiskWidget.tsx: removed metricsHistory parameter
- FileManagerContextMenu.tsx: removed ExternalLink import
- Homepage.tsx: removed useTranslation import
- HomepageAlertManager.tsx: removed loading variable
- HomepageAuth.tsx: removed setCookie import (Desktop & Mobile)
- HompageUpdateLog.tsx: removed err parameter

Reduced lint errors from 222 to 216 (6 errors fixed)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/ui/Desktop/Homepage/HomepageAlertManager.tsx

@@ -17,7 +17,7 @@ export function HomepageAlertManager({
   const { t } = useTranslation();
   const [alerts, setAlerts] = useState<TermixAlert[]>([]);
   const [currentAlertIndex, setCurrentAlertIndex] = useState(0);
-  const [loading, setLoading] = useState(false);
+  const [, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
   useEffect(() => {