fix: Add datetime casts to Order model and null check in view

- Add casts array to Order model for packing_completed_at, delivered_at, qr_generated_at
- Update ops order-detail view to safely handle null packing_completed_at
- Prevents 'Call to a member function format() on string' error

app/Models/Order.php

@@ -46,6 +46,17 @@ class Order extends Model
         'qr_generated_at',
     ];
 
+    protected function casts(): array
+    {
+        return [
+            'packing_completed_at' => 'datetime',
+            'delivered_at' => 'datetime',
+            'qr_generated_at' => 'datetime',
+            'created_at' => 'datetime',
+            'updated_at' => 'datetime',
+        ];
+    }
+
     public function user()
     {
         return $this->belongsTo(User::class);