Topaz alignment spike — mapping doc + green e2e example

Closes FLEX-WP-0005 T04. Validates ADR-003's commitment to shape the
standalone core for cheap Topaz adapter work.

Spike output:
- docs/topaz-mapping-spike.md — vocabulary map (subject, group, tenant,
  knowledge_base, document, plus parent / owner_team / reader / steward /
  member relations), Rego module shape, decision envelope, wire-protocol
  ranking (gRPC primary, REST fallback, embedding rejected), schema
  restatement recommendation, implications for FLEX-WP-0002 / 0004.
- examples/topaz/ — runnable docker-compose deploying Topaz with the
  flex-auth-shaped manifest. seed and probe one-shots cover three
  scenarios: alice (steward) allow, bob (group→reader) allow, eve
  (outsider) deny. End-to-end green on 2026-05-16:

    probe: steward-allow OK (check=true)
    probe: reader-allow  OK (check=true)
    probe: outsider-deny OK (check=false)
    probe: all checks passed

Key findings recorded as Implementation Notes in the spike doc:
- Rego input contract bridging (Topaz raw shape ↔ flex-auth canonical
  shape) is adapter scope, not core scope.
- Topaz identity objects are a Topaz convention; the adapter
  materializes them at directory import time.
- Directory-only permission resolution is sufficient for the common
  case; Rego is reserved for context-dependent decisions.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workplans/FLEX-WP-0005-foundations-and-topaz-alignment.md

@@ -125,7 +125,7 @@ flex-auth as the canonical owner of the manifest shape.
 
 ```task
 id: FLEX-WP-0005-T004
-status: in_progress
+status: done
 priority: high
 state_hub_task_id: "b8a314c3-e98e-4093-bb11-ab8546b8d79b"
 ```