Make admin modals non-dismissible with confirmation

Prevent accidental data loss by requiring confirmation before closing any admin modal via backdrop click. Applied to all admin pages with dialogs.

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Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/pages/admin/AdminProducts.tsx

@@ -267,7 +267,13 @@ export default function AdminProducts() {
           )}
         </div>
 
-        <Dialog open={dialogOpen} onOpenChange={setDialogOpen}>
+        <Dialog open={dialogOpen} onOpenChange={(open) => {
+          if (!open) {
+            const confirmed = window.confirm('Tutup dialog? Data yang belum disimpan akan hilang.');
+            if (!confirmed) return;
+          }
+          setDialogOpen(open);
+        }}>
           <DialogContent className="max-w-3xl max-h-[90vh] overflow-y-auto border-2 border-border">
             <DialogHeader>
               <DialogTitle>{editingProduct ? 'Edit Produk' : 'Produk Baru'}</DialogTitle>