feat(site): enhance monitoring dashboard and public status pages

Implement incident tracking for public status pages, improve the monitoring
dashboard UI with better grouping and loading states, and refine domain
resolution logic.

- feat(hub): add incident support to public status pages
- feat(hub): implement immediate monitor checks on creation and resume
- feat(hub): improve domain status detection using DNS fallback when WHOIS fails
- feat(site): redesign monitoring dashboard with categorized cards
- feat(site): add incident detail view and management in the dashboard
- feat(site): add active incidents section to public status pages
- feat(site): add "Add System" functionality to systems table
- refactor(site): improve calendar view responsiveness and loading states
- style(site): add skeleton components for better UX during data fetching

internal/site/src/components/ui/skeleton.tsx

@@ -0,0 +1,15 @@
+import { cn } from "@/lib/utils"
+
+function Skeleton({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) {
+  return (
+    <div
+      className={cn("animate-pulse rounded-md bg-primary/10", className)}
+      {...props}
+    />
+  )
+}
+
+export { Skeleton }