cuda graphs

[roiser]

Idea or splitting ME calculations into individual kernels and use graphs for their dependencies. First we try on eemumu by hand then move upstream and see what happens for more complex cases.

[valassi]

CUDA Graphs is fully functional in PR #1066. (But I actually propose to merge #1066 and possibly remove CUDA graphs, as it seems rather useless at least for the purpose I used it for, orchestrating groups of Feynman diagrams). Full documentation in https://arxiv.org/abs/2510.05392v2 that should appear tomorrow.