feat(dashboard): add cPanel-style server info bar and bump to v0.4.4

Adds a compact info strip at the top of the NixPanel dashboard showing
Username, Hostname, OS, NixPanel Version, Load Averages (live via
WebSocket), and Server Monitoring alert count. Alert count is derived
from GET /api/nixserver/services — green "All Clear" when all services
are running, amber "N Alerts" for any stopped/failed service.

Also fixes the version footer error state in Layout.tsx (versionError
→ "Version unavailable" fallback with retry button) so the spinner no
longer hangs indefinitely when the version API is unreachable.

server/src/app.ts

@@ -73,7 +73,7 @@ export async function buildApp() {
 
   fastify.get('/api/health', async () => ({
     status: 'ok',
-    version: '0.4.3',
+    version: '0.4.4',
     timestamp: new Date().toISOString(),
   }))