improved property system to differentiate between unknown and zero

cookbook/migrations/0212_alter_property_property_amount.py

@@ -0,0 +1,18 @@
+# Generated by Django 4.2.7 on 2024-02-18 07:51
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('cookbook', '0211_recipebook_order'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='property',
+            name='property_amount',
+            field=models.DecimalField(decimal_places=4, default=None, max_digits=32, null=True),
+        ),
+    ]