d9b0d5d599
- Extend RegistrationMode::Mixnet to include client_ed25519_pubkey and client_x25519_pubkey for nym address construction - Add LpGatewayData struct containing gateway_identity and gateway_sphinx_key for SURB reply routing - Add lp_gateway_data field to LpRegistrationResponse for mixnet mode - Implement success_mixnet() constructor for mixnet registrations - Update gateway registration to insert clients into ActiveClientsStore for SURB reply delivery, matching the websocket flow