BLAST-ImpactX

This skill should be used when the user asks to "update element benchmarks", "add missing element tests", "audit element test coverage", "add a benchmark for <element>", or to check that every lattice element under `src/elements/` has matching entries in the three Python element-coverage tests (benchmark, serialization, reversibility) and that spin-capable elements carry the spin/nospin parametrization. Also covers re-running those three tests after edits.