objective-battery top-up: 10 variant cores (x3 stack + isolates + CaptionBert-verbatim replication) + descent-diagnostic ledgers + VARIANTS.md findings table

vit-captionbank ship: two-stage cores (reusable) + bank expansions + cotrained pairs + frames + fidelity-gated loader + complete ledgers incl. the preregistered probe refutation with full controls

initial commit