Add split-muon BIB production script

[henrygreenhut]

Summary

Adds generation/bib/split_muon_bib.py to produce the BIB banks needed to overlay muon-producing decay histories separately from the rest of the BIB.

The script:

• Scans an unrotated, mother-split GEN library and identifies complete decay histories containing at least one detector-bound muon (abs(PDG) == 13).
• Produces a bulk-norm42 component after removing those histories.
• Produces an unrotated, one-history-per-entry muon component.
• Produces one-entry files containing a Poisson-distributed number of unrotated muon-producing histories for use with the current OverlayTimingRandomMix.
• Records source-cycle and source-entry provenance and validates the output partition.