Allow entering zero (0 € or so) as an amount
Background
In Cospend online I can enter 0.0 as an amount.
Use case: This is e.g. useful to track expenses, which are, due to a discount or so, actually zero (on communities like pepper/German MyDealz or so called "freebies") or, which are sometimes not zero, but reoccurring or so. There may be other use cases.
User story: I as a Cospend user, want to enter 0.0 as an amount to track discounted " expenses.
solution/proposal
I want to save an expense with 0 as a value "spend".
currently
The save button is just not shown as long as the value is 0. So I can UI-wise only save stuff if it equals zero.
Even a "hack" like entering 5-5
does not work, as apparently the result is really calculated and so if it calculates/evaluates to 0, it cannot be saved.