EnrichmentMiddleware, AuthzMiddleware, IdentityEnricher, PermissionProvider,
and related types are removed from this module. They now live in
code.nochebuena.dev/go/httpauth, the provider-agnostic middleware layer.
AuthMiddleware is updated to call httpauth.SetTokenData, fulfilling the
integration contract between provider-specific auth and generic middleware.
This module now has a single responsibility: Firebase JWT verification.
BREAKING CHANGE: IdentityEnricher, PermissionProvider, EnrichmentMiddleware,
AuthzMiddleware, and WithTenantHeader are no longer exported from this package.
Import code.nochebuena.dev/go/httpauth for those identifiers.
rbac is a Tier 0 module (no micro-lib dependencies). The dependency line
incorrectly cited it as Tier 1. The module's own tier (4) is unchanged —
it remains the auth layer above the transport infrastructure.
