feat: Add staging banner to dev/test environment

- Add StagingBanner component that displays on dev/staging/test domains
- Shows warning that site is not production-ready
- Automatically detects staging environment via hostname or env vars
- Dismissible banner with smooth animations
- Only shows on dev.dk0.dev or other test domains

app/layout.tsx

@@ -7,6 +7,7 @@ import { AnalyticsProvider } from "@/components/AnalyticsProvider";
 import { ClientOnly } from "./components/ClientOnly";
 import BackgroundBlobsClient from "./components/BackgroundBlobsClient";
 import ChatWidget from "./components/ChatWidget";
+import { StagingBanner } from "@/components/StagingBanner";
 
 const inter = Inter({
   variable: "--font-inter",
@@ -33,6 +34,7 @@ export default function RootLayout({
         <AnalyticsProvider>
           <ToastProvider>
             <ClientOnly>
+              <StagingBanner />
               <BackgroundBlobsClient />
             </ClientOnly>
             <div className="relative z-10">{children}</div>