feat(admin): design system audit fixes

- Add CSS design tokens for consistency (--admin-danger-hover, --admin-accent-dot, shadow-md warm tone)
- Replace unicode icons with inline SVG (⋮, ✕, ▼, ▶)
- Consolidate duplicate PageHeader/AdminPageHeader components
- Standardize border-radius (rounded-xl → rounded-lg for ViewModeTabs)
- Remove hardcoded brand UUID in products page
- Replace hardcoded bg-red-600 with CSS variables in delete buttons
- Add AdminButton, AdminFilterTabs, AdminSearchInput, PageHeader design system components
- Fix GlassModal and AdminModal close button styling
- Remove duplicate 'New Lot' button on Route Trace dashboard

src/app/admin/orders/page.tsx

@@ -2,6 +2,7 @@ import AdminOrdersPanel from "@/components/admin/AdminOrdersPanel";
 import { getAdminUser } from "@/lib/admin-permissions";
 import { getAdminOrders } from "@/actions/orders";
 import AdminAccessDenied from "@/components/admin/AdminAccessDenied";
+import { PageHeader } from "@/components/admin/design-system";
 import { redirect } from "next/navigation";
 
 export const dynamic = "force-dynamic";
@@ -30,21 +31,18 @@ export default async function AdminOrdersPage() {
 
   return (
     <div className="min-h-screen bg-[var(--admin-bg)]">
-      {/* Header */}
       <div className="px-4 sm:px-6 md:px-8 pt-4 sm:pt-6">
-        <div className="flex items-center gap-3 mb-4">
-          <div className="flex h-10 w-10 sm:h-12 sm:w-12 items-center justify-center rounded-xl bg-emerald-600">
-            <svg className="h-5 w-5 sm:h-6 sm:w-6 text-white" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+        <PageHeader
+          title="Orders"
+          subtitle="Manage customer orders and pickup status"
+          icon={
+            <svg className="h-5 w-5 sm:h-6 sm:w-6" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
               <path d="M6 2 3 6v14a2 2 0 0 0 2 2h14a2 2 0 0 0 2-2V6l-3-4Z"/>
               <path d="M3 6h18"/>
               <path d="M16 10a4 4 0 0 1-8 0"/>
             </svg>
-          </div>
-          <div>
-            <h1 className="text-xl sm:text-2xl font-black text-[var(--admin-text-primary)] tracking-tight">Orders</h1>
-            <p className="text-xs text-[var(--admin-text-muted)]">Manage customer orders and pickup status</p>
-          </div>
-        </div>
+          }
+        />
       </div>
 
       {/* Content */}