BoxSeed doesn't update seed number, increment/decrement is unusable

[morgan55555]

BoxSeed needs to update, if seed is random/increment/decrement. Also, real max seed number for KSampler is bigger, than MAX_SAFE_INTEGER, which is current limit for SDFX AI. And why we can enter number only in fixed mode, this should be allowed even in increment/decrement (if it will be updated)