fix: add proper empty state to Peak Hours with icon and description

components/dashboard/PeakHours.tsx

@@ -279,9 +279,15 @@ export default function PeakHours({ siteId, dateRange }: PeakHoursProps) {
           )}
         </>
       ) : (
-        <div className="flex-1 min-h-[270px] flex flex-col items-center justify-center text-center gap-3">
-          <p className="text-sm text-neutral-400">
-            No data available for this period
+        <div className="flex-1 min-h-[270px] flex flex-col items-center justify-center text-center px-6 py-8 gap-3">
+          <div className="rounded-full bg-neutral-800 p-4">
+            <Clock className="w-8 h-8 text-neutral-400" />
+          </div>
+          <h4 className="font-semibold text-white">
+            No peak hours yet
+          </h4>
+          <p className="text-sm text-neutral-400 max-w-xs">
+            Once your site receives traffic, this heatmap will show when your visitors are most active.
           </p>
         </div>
       )}