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/not-found.js

@@ -0,0 +1,36 @@
+'use client';
+
+import { motion } from 'framer-motion';
+import { AlertTriangle, RefreshCw, Home } from 'lucide-react';
+import Link from 'next/link';
+
+export default function NotFound() {
+  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="mb-6">
+          <svg viewBox="0 0 200 160" className="w-64 h-48 mx-auto">
+            <circle cx="100" cy="80" r="70" fill="#fef3c7" />
+            <text x="100" y="95" textAnchor="middle" fontSize="60" fontWeight="bold" fill="#f59e0b">404</text>
+            <circle cx="80" cy="110" r="8" fill="#92400e" />
+            <circle cx="120" cy="110" r="8" fill="#92400e" />
+            <path d="M85 130 Q100 120 115 130" stroke="#92400e" strokeWidth="3" fill="none" strokeLinecap="round" />
+          </svg>
+        </div>
+        <h2 className="text-2xl font-bold text-gray-900 mb-2">الصفحة غير موجودة</h2>
+        <p className="text-gray-500 mb-8">عذراً، الصفحة التي تبحث عنها غير متوفرة</p>
+        <Link
+          href="/"
+          className="inline-flex items-center gap-2 bg-amber-500 text-white px-6 py-3 rounded-xl font-medium hover:bg-amber-600 transition-colors"
+        >
+          <Home className="w-5 h-5" />
+          العودة للرئيسية
+        </Link>
+      </motion.div>
+    </div>
+  );
+}