Brummel
cffc297e9a
Three tasks for #146: (1) RunManifest.instrument serde-widened field + compat-mirror lockstep + thread all in-workspace literals + back-compat tests; (2) aura-registry FamilyKind::CrossInstrument + the R-only generalization reduction (worst-case floor + sign-agreement + breakdown) + check_r_metric + two RegistryError variants; (3) aura-cli generalize subcommand (single-cell stage1-r candidate x instrument list), data-free arity/metric refusals, a gated-skip cross-instrument E2E. fieldtests/ confirmed outside the workspace compile set; FamilyKind has no exhaustive match (serde-derive); only RegistryError's Display match is a gate. refs #146