feat: show last update check timestamp on dashboard

frontend/src/views/DashboardView.tsx

@@ -300,9 +300,22 @@ export function DashboardView() {
         {/* Card 2: Updates & Wartung (1 column wide) */}
         <div className="rounded-2xl border border-border/60 bg-card/45 backdrop-blur-md p-5 shadow-lg shadow-black/15 flex flex-col justify-between">
           <div className="space-y-4">
-            <div className="flex items-center gap-2">
-              <ShieldAlert className="h-4.5 w-4.5 text-primary" />
-              <h2 className="text-sm font-semibold tracking-wide uppercase text-foreground">Updates &amp; Pflege</h2>
+            <div className="flex items-center justify-between flex-wrap gap-2 border-b border-border/20 pb-2">
+              <div className="flex items-center gap-2">
+                <ShieldAlert className="h-4.5 w-4.5 text-primary" />
+                <h2 className="text-sm font-semibold tracking-wide uppercase text-foreground">Updates &amp; Pflege</h2>
+              </div>
+              {updates?.last_check && (
+                <span className="text-[9px] text-muted-foreground/80 font-mono">
+                  Zuletzt gesucht: {new Date(updates.last_check * 1000).toLocaleString("de-DE", {
+                    day: "2-digit",
+                    month: "2-digit",
+                    year: "numeric",
+                    hour: "2-digit",
+                    minute: "2-digit"
+                  })}
+                </span>
+              )}
             </div>
             
             {updates ? (