feat(keycloak): M4.3 — Admin API adapter + claim resolver

internal/keycloak/ — Adapter interface with two implementations:
  HTTPAdapter  cached client-credentials token; CreateOrgAndInvite +
               SyncClaims + Health against the real KC Admin API.
  Mock         in-process map for unit tests + dev convenience when
               KEYCLOAK_ADMIN_URL is empty. Used by the eachStore harness.

POST /v1/tenants now accepts admin_email + admin_name. When set, the
adapter creates a KC organization, invites the user as IT_ADMIN, and
triggers VERIFY_EMAIL + UPDATE_PASSWORD. Response wraps the tenant
with TenantCreated{tenant, invite_url}. KC failures DO NOT roll the
tenant back — they emit a keycloak.provision_failed audit event.
Successful invites emit keycloak.invite_sent.

POST /v1/internal/keycloak/claims resolves a tenant's current claim
bundle (tenant_id, slug, products, plan, status). Lookup chain:
body.tenant_id → body.tenant_slug → user_attrs.tenant_id →
user_attrs.tenant_slug.

Config: KEYCLOAK_ADMIN_URL / REALM / CLIENT_ID / CLIENT_SECRET;
empty URL falls back to Mock.

Tests:
  internal/keycloak/mock_test.go     conflict surfacing, FailNext hook,
                                     SyncClaims persistence.
  internal/keycloak/client_test.go   HTTPAdapter against an in-process
                                     stub KC: health, full create-org-
                                     and-invite, conflict, token-cache,
                                     401 retry, ErrUnavailable.
  internal/server/keycloak_test.go   eachStore integration: provisions
                                     via mock; failure path emits
                                     provision_failed audit; claims
                                     endpoint via every lookup variant
                                     + 404 + 400.

OpenAPI extended with TenantCreated + Claims schemas and the new
claims endpoint. Contract test asserts the new path.

CI: include internal/keycloak/... in the test package list so
HTTPAdapter coverage counts. Total project line coverage: 71.6%.

Refs: M4.3

internal/server/openapi_test.go

@@ -44,6 +44,7 @@ func TestOpenAPISpec_loadsAndIsConsistent(t *testing.T) {
 		{"GET", "/v1/api-keys?tenant_id=00000000-0000-0000-0000-000000000001"},
 		{"GET", "/v1/catalog"},
 		{"GET", "/v1/audit?limit=10"},
+		{"POST", "/v1/internal/keycloak/claims"},
 	}
 	for _, c := range cases {
 		req := newRequest(t, c.method, c.path)