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

components/StagingBanner.tsx

@@ -0,0 +1,62 @@
+'use client';
+
+import React from 'react';
+import { motion } from 'framer-motion';
+import { AlertTriangle, X } from 'lucide-react';
+
+export function StagingBanner() {
+  const [isVisible, setIsVisible] = React.useState(true);
+  const [isStaging, setIsStaging] = React.useState(false);
+  
+  // Check if we're in staging/dev environment (client-side check)
+  React.useEffect(() => {
+    if (typeof window !== 'undefined') {
+      const hostname = window.location.hostname;
+      const baseUrl = process.env.NEXT_PUBLIC_BASE_URL || '';
+      
+      const staging = 
+        hostname.includes('dev') ||
+        hostname.includes('staging') ||
+        hostname.includes('test') ||
+        baseUrl.includes('dev') ||
+        baseUrl.includes('staging') ||
+        baseUrl.includes('test');
+      
+      setIsStaging(staging);
+    }
+  }, []);
+
+  if (!isStaging || !isVisible) {
+    return null;
+  }
+
+  return (
+    <motion.div
+      initial={{ y: -100, opacity: 0 }}
+      animate={{ y: 0, opacity: 1 }}
+      exit={{ y: -100, opacity: 0 }}
+      className="fixed top-0 left-0 right-0 z-50 bg-gradient-to-r from-yellow-500 via-orange-500 to-red-500 text-white shadow-lg"
+    >
+      <div className="container mx-auto px-4 py-2 md:py-3 flex items-center justify-between gap-4">
+            <div className="flex items-center gap-3">
+          <AlertTriangle className="w-5 h-5 animate-pulse flex-shrink-0" />
+          <div className="flex-1 min-w-0">
+            <p className="font-bold text-sm md:text-base">
+              🧪 TEST / DEVELOPMENT VERSION
+            </p>
+            <p className="text-xs md:text-sm text-white/90">
+              This is a staging environment. Not production-ready. Data may be unstable.
+            </p>
+          </div>
+        </div>
+        <button
+          onClick={() => setIsVisible(false)}
+          className="p-1 hover:bg-white/20 rounded transition-colors"
+          aria-label="Close banner"
+        >
+          <X className="w-4 h-4" />
+        </button>
+      </div>
+    </motion.div>
+  );
+}