v0.16.1

Raises the flopscope floor to 0.12.1, which makes a symmetry tag describe the
buffer it is attached to. No already-scored submission is repriced by it: the
one change that moves a price is full/full_like with a non-scalar
fill_value, and no scored submission in the current phase passes one.

The digit is a patch by decision, not by detection. cz reports MINOR,
because mc_flops_per_sample() below is a new public API. It publishes the
cost of one Monte-Carlo sample -- the MC@B_m baseline submissions are compared
against -- which was previously not stated anywhere participants could check.
It adds a helper and changes no score.

Feat

• budget: publish the Monte-Carlo per-sample cost model

Fix

• deps: raise the flopscope floor to 0.12.1