Include total stock in PartBrief serializer

InvenTree/part/models.py

@@ -379,7 +379,7 @@ class Part(models.Model):
 
         total -= self.allocation_count
 
-        return total
+        return max(total, 0)
 
     def isStarredBy(self, user):
         """ Return True if this part has been starred by a particular user """

InvenTree/part/serializers.py

@@ -50,6 +50,7 @@ class PartBriefSerializer(serializers.ModelSerializer):
             'url',
             'full_name',
             'description',
+            'total_stock',
             'available_stock',
             'image_url',
         ]