Ratify a2mliser (in) + contractiles-a2-lab (cross-ref)

[hyperpolymath]

Ratify two membership decisions recorded in this rebuild:

• a2mliser — confirmed as a tooling member submodule.
• contractiles-a2-lab — remains a private project; not a member submodule, recorded only as a (related ...) cross-reference in .machine_readable/6a2/ECOSYSTEM.a2ml.

scripts/check-membership.sh enforces both (a2mliser pinned; contractiles-a2-lab must not be a submodule).