Add loading.js and error.js for all routes, secure admin page with 404

- Added loading.js (dark/light variants) for all 14 routes
- Added error.js (dark/light variants) for all 14 routes
- Added global not-found.js and loading.js at root
- Admin page shows 404 illustration for non-admin users instead of redirecting

app/error.js

@@ -0,0 +1,39 @@
+'use client';
+
+import { motion } from 'framer-motion';
+import { AlertTriangle, RefreshCw, Home } from 'lucide-react';
+import Link from 'next/link';
+
+export default function GlobalError({ error, reset }) {
+  return (
+    <div className="min-h-screen bg-gray-50 flex items-center justify-center p-4">
+      <motion.div
+        initial={{ opacity: 0, y: 20 }}
+        animate={{ opacity: 1, y: 0 }}
+        className="text-center max-w-md"
+      >
+        <div className="w-24 h-24 bg-red-100 rounded-full flex items-center justify-center mx-auto mb-6">
+          <AlertTriangle className="w-12 h-12 text-red-500" />
+        </div>
+        <h2 className="text-2xl font-bold text-gray-900 mb-2">حدث خطأ غير متوقع</h2>
+        <p className="text-gray-500 mb-8">نعتذر عن هذا الإزعاج، يرجى المحاولة مرة أخرى</p>
+        <div className="flex gap-3 justify-center">
+          <button
+            onClick={reset}
+            className="flex items-center gap-2 bg-amber-500 text-white px-6 py-3 rounded-xl font-medium hover:bg-amber-600 transition-colors"
+          >
+            <RefreshCw className="w-5 h-5" />
+            إعادة المحاولة
+          </button>
+          <Link
+            href="/"
+            className="flex items-center gap-2 bg-gray-200 text-gray-700 px-6 py-3 rounded-xl font-medium hover:bg-gray-300 transition-colors"
+          >
+            <Home className="w-5 h-5" />
+            الرئيسية
+          </Link>
+        </div>
+      </motion.div>
+    </div>
+  );
+}