Add admin dashboard pages and restructure admin route

Introduces new admin dashboard pages for alerts, bans, invites, orders, settings, status, and vendors under app/dashboard/admin/. Moves the main admin page to the new dashboard structure and adds a shared admin layout. Updates sidebar configuration and adds supporting components and hooks for admin features.

config/admin-sidebar.ts

@@ -0,0 +1,27 @@
+import { Home, Shield, Users, Ban, UserPlus, Package, Settings, BarChart3, AlertTriangle } from "lucide-react"
+
+export const adminSidebarConfig = [
+  {
+    title: "Overview",
+    items: [
+      { name: "Admin Dashboard", href: "/dashboard/admin", icon: Home },
+      { name: "System Status", href: "/dashboard/admin/status", icon: BarChart3 },
+    ],
+  },
+  {
+    title: "User Management",
+    items: [
+      { name: "All Vendors", href: "/dashboard/admin/vendors", icon: Users },
+      { name: "Invite Vendor", href: "/dashboard/admin/invite", icon: UserPlus },
+      { name: "Ban Users", href: "/dashboard/admin/ban", icon: Ban },
+    ],
+  },
+  {
+    title: "System",
+    items: [
+      { name: "Recent Orders", href: "/dashboard/admin/orders", icon: Package },
+      { name: "System Alerts", href: "/dashboard/admin/alerts", icon: AlertTriangle },
+      { name: "Settings", href: "/dashboard/admin/settings", icon: Settings },
+    ],
+  },
+]