nfs4.1: acceptance — live vers=4.1 mount gate + Trident/Ansible + v3 regression

[hartsock]

Goal

Prove the v4.1 data plane against real clients and lock it behind a live gate.

Scope

• Live (root-only) test: mount -t nfs -o vers=4.1 → Connectathon-style basic
  ops (create/read/write/append/rename/remove/lock/readdir).
• Trident / netapp-ontap SDK / Ansible drive protocols/nfs/services +
  export-policies end-to-end against the REST surface.
• The NFSv3 reconstitution/live suite still passes (no regression).
• Wire the live gate into CI on the ARC runner (like the recon gate), marked
  live/root-only; hermetic CI unaffected.

Dependencies

#58.

Acceptance

• Green live v4.1 mount gate + green v3 regression, both in CI.