fix(people): keep authenticated tenant authority structurally detached after access #331

Finding

Canonical governed-People owner #55 detached the constructor input in #330, but still retained the reconstructed mutable uuid.UUID object as the public AuthenticatedPrincipal.tenant_record_id field. A consumer could read that field, mutate the returned UUID through low-level object.__setattr__, and change the principal's later tenant view after authentication.

This violates the existing scalar-authority invariant: trust-bearing UUID authority must be retained as interpreter-immutable scalar evidence, with public UUID views reconstructed fresh. It is distinct from #330, which proved constructor-time caller-alias detachment and exact scalar/type validation but did not prove post-construction field access could not expose the retained UUID object.

Repair lineage

• RED contract: 38eb24179d5dbad5d102ebc10f30031ec013bbbf.
• Causal repair: 0e93773f099b7925a67c63a2079aa4a842ff8d9a retains tenant authority as tuple-backed exact built-in integer evidence and reconstructs a fresh UUID on access.
• Edge coverage: cbd2cf16eb746e3712f9d0caf746fa5884828862 revalidates retained tuple payload and covers malformed low-level tuple construction.
• fix(people): require exact bearer-header scalar before parser dispatch #332 then advanced the same canonical owner to current fix(people): harden governed People reads #55 exact head 00d16ec6ef8db8fd0eaa7d65fd0666e9a2f9de6d without weakening fix(people): keep authenticated tenant authority structurally detached after access #331.
• Current ordinary-forward descendants: feat(people): add purpose-bound Employment history read #149 2b4689defb6ecf5f817ac88337070ee77b58f418, feat(people): expose employment history HTTP read #155 0a084b16da4dd21e99dcd6b4d3274ad1bf38c2b1, feat(people): add PostgreSQL Employment-history read adapter #156 563b538b7483dda5ec83c025c30311ccbb034fad.

Fresh final-head Foundation/Security/CodeQL are queued and SAST is pending. No predecessor evidence transfers, hosted GREEN, self/model approval, force-push, destructive rebase, or gate weakening is claimed. Keep this issue open until final #55 protected acceptance and integration.