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

internal/keycloak Adapter (HTTPAdapter + Mock). POST /v1/tenants now provisions a KC organization + IT_ADMIN invite when admin_email is set; KC failures emit keycloak.provision_failed but don't roll back. POST /v1/internal/keycloak/claims resolves the current claim bundle for any (tenant_id|tenant_slug|user_attrs.*) lookup. Mock used in tests + when KEYCLOAK_ADMIN_URL is empty. HTTPAdapter tested against an in-process stub KC (httptest.Server).

Refs: M4.3

internal/server/server_test.go

@@ -21,6 +21,7 @@ import (
 	tcpostgres "github.com/testcontainers/testcontainers-go/modules/postgres"
 
 	"gitea.meghsakha.com/platform/tenant-registry/internal/config"
+	"gitea.meghsakha.com/platform/tenant-registry/internal/keycloak"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/server"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
 	"gitea.meghsakha.com/platform/tenant-registry/migrations"
@@ -33,6 +34,7 @@ type testHarness struct {
 	srv    *httptest.Server
 	store  store.Store
 	tenant *store.Tenant // pre-created acme tenant
+	kcMock *keycloak.Mock
 }
 
 func (h *testHarness) Close() {
@@ -131,14 +133,19 @@ func newPostgresHarness(t *testing.T) *testHarness {
 func wireHarness(t *testing.T, s store.Store, seed *store.Tenant) *testHarness {
 	t.Helper()
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
+	mock := keycloak.NewMock()
 	handler := server.NewRouter(&server.Server{
-		Cfg: &config.Config{Env: "dev"}, Log: logger, Store: s,
+		Cfg:      &config.Config{Env: "dev"},
+		Log:      logger,
+		Store:    s,
+		Keycloak: mock,
 	})
 	return &testHarness{
 		t:      t,
 		srv:    httptest.NewServer(handler),
 		store:  s,
 		tenant: seed,
+		kcMock: mock,
 	}
 }