show total budget on the view, over_budget check
test: not over budget
new integration test: it can block
test: it can pass
set budget per line, compute on the order
store the total budget
make mock stricter with spec_set

That way I can read and write only attributes of the real logistic
source.
refactor budget_amount -> budget_tot_price

So that it is consistent with the same field on the logistic request.
Make a test stricter to drive this change.
check it has no budget holder
test has budget holder
configure no budget holder exception