Align approval registrations to the tenant:platform decision

Operator decision 5ed3fb35-eca9-413a-82b9-95171ba85bf6 accepts tenant:platform
as the platform management tenant for the Glas approval chain, requiring exact
spelling across the approval store, the service-client JWT claim and the
lifecycle CheckRequest.

Changes the tenant field on secrets-engine-approval and approval-engine-operator
only, in the registration fixture and the provisioning packet. Unrelated clients
and the human directory default keep tenant:coulomb, and no audience, scope,
subject, role, lifetime or MFA grant changes.

Adds issuance evidence that the approval shape emits tenant:platform exactly and
never an alias the caller requests, that the OpenBao client gains no
cross-tenant reach, and a fixture guard pinning every reviewed client's tenant.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NV9oijZukGyGbRQGGKnK4P

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 713576@bnt-lap001
Assistant-Session: 384c511d-9bce-4cb8-a676-2aef6c0c8df6

workplans/KEY-WP-0015-scope-intent-assessment.md

@@ -9,6 +9,7 @@ owner: codex
 topic_slug: scope-intent-assessment
 created: "2026-09-05"
 updated: "2026-09-05"
+state_hub_workstream_id: "14a7312b-ec92-5640-8b26-cbaa4753c18e"
 ---
 
 ## Inventory implementation and document scope gaps
@@ -17,6 +18,7 @@ updated: "2026-09-05"
 id: KEY-WP-0015-T01
 status: done
 priority: medium
+state_hub_task_id: "99be1489-d9e5-53b1-9c82-75dc961131f7"
 ```
 
 Reviewed source revision b989de4, INTENT, SCOPE, runtime composition, authentication