Brummel
45b8e2b28b
Second cycle of the inferential-validation milestone. Adds an opt-in plateau selection objective: optimize_plateau beside optimize/optimize_deflated scores each grid member by the mean/worst of its grid-neighbourhood metric and argmaxes the smoothed surface (mixed-radix neighbours over GridSpace axis_lens, passed as an argument not a SweepFamily field). Strictly opt-in via --select <argmax|plateau:mean|plateau:worst>, default argmax (C23 byte-preserving). Reconciles the shared RunManifest.selection carrier with #144's landed reality: the selection RULE (argmax vs plateau) and the deflation ANNOTATION are orthogonal, so FamilySelection is extended — deflation fields become Option, SelectionMode gains PlateauMean/PlateauWorst (the reserved slot), and neighbourhood_score/n_neighbours are added. A small wire change to the one-cycle-old type; legacy lines still load. RandomSpace plateau refused (exit 2 — no lattice); kNN deferred. Grounding-check PASS (12 assumptions ratified). refs #145