Handle a successful provider authentication (login). Called by a
Passport strategy's verify callback after the provider OAuth
succeeds; the find-or-create path is parameterized by provider.
which login provider authenticated
normalized profile (Google) / profile+tokens (Twitch)
Passport callback (principal carries authProvider)
Send a fully-stamped envelope to a specific WebSocket
connection. Parallel to sendMessageToSocket; carries
its frameId already (stamped per-Interactive by Application).
Send a message to a specific WebSocket connection.
The socket ID to send to
The message object to send
Backend interface for Application callbacks.