Provides AuthMiddleware (calls httpauth.SetTokenData, accepts Verifier or Signer),
IssueTokenPair (access + refresh tokens as jwt.MapClaims, custom claims at top
level for ClaimsPermissionProvider compatibility), RefreshTokenPair (blacklist
check + rotation + re-issue), and Signer/Verifier implementations for HMAC-SHA256
and RSA-SHA256 including PEM loaders and a public-key-only Verifier for read-only
microservices.
