Support multiple named secrets in [secrets] config section. During
FakeTLS handshake each secret is tried until HMAC validates. Matched
secret name is logged and used for per-user statistics tracking.
Built-in HTTP stats API (configurable via api-bind-to) exposes
GET /stats with per-user connection counts, bytes in/out, and
last-seen timestamps.
Backward compatible: single "secret" config key still works.
Alexey Dolotov