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

internal/keycloak/ — Adapter interface with two implementations:
  HTTPAdapter  pgxpool-style real Admin API client with cached client-
               credentials token (auto-refresh, 401 retry).
  Mock         in-process map for unit tests + dev convenience when
               KEYCLOAK_ADMIN_URL is empty. Used by the eachStore harness.

Adapter contract (adapter.go):
  CreateOrgAndInvite(ctx, InviteInput) (*InviteResult, error)
    Creates a KC organization, an IT_ADMIN user, adds the user as a
    member, triggers VERIFY_EMAIL + UPDATE_PASSWORD execute-actions
    email. Atomic from the caller's PoV; partial failures surface as
    typed errors (ErrOrgConflict, ErrUserConflict, ErrUnauthorized,
    ErrUnavailable).
  SyncClaims(ctx, userID, Claims) error
    Pushes tenant_id / tenant_slug / org_roles / products / plan /
    tenant_status into the user's KC attributes — the same shape the
    realm's protocol mappers project into JWTs.
  Health(ctx) error
    Pings /admin/serverinfo; wired into readyz.

Wiring:
  POST /v1/tenants now accepts admin_email + admin_name. When set, the
  adapter creates the org and invites the user. Response wraps the
  tenant with the new TenantCreated{tenant, invite_url} shape so dev
  testers can use the action-token URL without waiting for the email.
  KC failures DO NOT roll the tenant back — they emit a
  keycloak.provision_failed audit event so the operator can resend.
  Successful invites emit keycloak.invite_sent.

  POST /v1/internal/keycloak/claims resolves a tenant's current claim
  bundle. Lookup chain: body.tenant_id → body.tenant_slug →
  body.user_attrs.tenant_id → body.user_attrs.tenant_slug. The realm's
  protocol mapper calls this at token issuance, or operators on demand.

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

OpenAPI: TenantCreated + Claims schemas added; /v1/internal/keycloak/claims
documented. Contract test extended to cover the new endpoint.

Tests:
  internal/keycloak/mock_test.go    Mock semantics: conflict surfacing,
                                    FailNext hook, SyncClaims persistence.
  internal/server/keycloak_test.go  KC provisioning end-to-end via
                                    eachStore: invite_url returned,
                                    mock records, invite_sent audit;
                                    failure path emits provision_failed
                                    but tenant still lands; claims
                                    endpoint resolves via tenant_id /
                                    tenant_slug / user_attrs / 404 / 400.

The real-KC integration test (against a testcontainers-spun KC 26)
lands in a follow-up — gating it behind KEYCLOAK_INTEGRATION=1 + a
slower nightly CI is cleaner than baking 30s+ of KC boot into every PR.

Refs: M4.3

internal/server/server.go

@@ -1,7 +1,7 @@
 // Package server wires the HTTP surface for tenant-registry.
 //
 // All routes are registered in NewRouter; per-concern handlers live in
-// peer files (tenants.go, catalog.go, apikeys.go, audit.go).
+// peer files (tenants.go, catalog.go, apikeys.go, audit.go, keycloak.go).
 package server
 
 import (
@@ -9,14 +9,16 @@ import (
 	"net/http"
 
 	"gitea.meghsakha.com/platform/tenant-registry/internal/config"
+	"gitea.meghsakha.com/platform/tenant-registry/internal/keycloak"
 	"gitea.meghsakha.com/platform/tenant-registry/internal/store"
 )
 
 // Server bundles the dependencies every handler needs.
 type Server struct {
-	Cfg   *config.Config
-	Log   *slog.Logger
-	Store store.Store
+	Cfg      *config.Config
+	Log      *slog.Logger
+	Store    store.Store
+	Keycloak keycloak.Adapter // never nil — main wires Mock when KC env is unset
 }
 
 // NewRouter builds the http.Handler with logging middleware applied.
@@ -34,9 +36,7 @@ func NewRouter(s *Server) http.Handler {
 	mux.HandleFunc("POST /v1/tenants/{id}/activate", s.activateTenant)
 	mux.HandleFunc("POST /v1/tenants/{id}/cancel", s.cancelTenant)
 
-	// entitlements — top-level path so it doesn't conflict with
-	// /v1/tenants/by-slug/{slug} (Go 1.22 ServeMux can't disambiguate
-	// /v1/tenants/{id}/products vs /v1/tenants/by-slug/{slug=products}).
+	// entitlements
 	mux.HandleFunc("GET /v1/entitlements", s.listTenantProducts)
 
 	// catalog
@@ -44,8 +44,7 @@ func NewRouter(s *Server) http.Handler {
 	mux.HandleFunc("POST /v1/catalog/request", s.catalogRequest)
 	mux.HandleFunc("POST /v1/catalog/trial-request", s.catalogTrialRequest)
 
-	// api keys — same disambiguation: list lives at /v1/api-keys?tenant_id=X
-	// instead of /v1/tenants/{id}/api-keys.
+	// api keys
 	mux.HandleFunc("POST /v1/api-keys", s.createAPIKey)
 	mux.HandleFunc("GET /v1/api-keys", s.listAPIKeys)
 	mux.HandleFunc("DELETE /v1/api-keys/{id}", s.revokeAPIKey)
@@ -55,6 +54,12 @@ func NewRouter(s *Server) http.Handler {
 	mux.HandleFunc("POST /v1/audit", s.appendAudit)
 	mux.HandleFunc("GET /v1/audit", s.listAudit)
 
+	// keycloak claims refresh — the URL the protocol mapper would call at
+	// token issuance to grab the up-to-date entitlement bundle. Today the
+	// dev realm projects user attributes (set by SyncClaims) — this is
+	// the "pull" complement for when the realm is reconfigured to fetch.
+	mux.HandleFunc("POST /v1/internal/keycloak/claims", s.kcClaims)
+
 	return logRequest(s.Log)(mux)
 }
 
@@ -67,5 +72,9 @@ func (s *Server) readyz(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusServiceUnavailable, "store_unavailable", err.Error())
 		return
 	}
+	if err := s.Keycloak.Health(r.Context()); err != nil {
+		writeError(w, http.StatusServiceUnavailable, "keycloak_unavailable", err.Error())
+		return
+	}
 	writeJSON(w, http.StatusOK, map[string]string{"status": "ready"})
 }