Billing: Build BillingData-Json in BillingData instead of anywhere else

Elwig/Helpers/Billing/EditBillingData.cs

@@ -67,7 +67,7 @@ namespace Elwig.Helpers.Billing {
             var attrs = context.WineAttributes.ToDictionary(a => a.AttrId, a => a);
 
             return dict3
-                .Select(e => new GraphEntry(e.Key, season, curves[e.Key], e.Value
+                .Select(e => new GraphEntry(e.Key, season.Precision, curves[e.Key], e.Value
                     .Select(s => new ContractSelection(vars[s[..2]], s.Length > 2 ? attrs[s[2..]] : null))
                     .ToList(), 50, 73, 140))
                 .ToList();