Feature Request: Handshake Event Callback

Feature Request: Handshake Event Callback: a task in LegoFlow-SWE (Harbor dataset). Problem Currently, after a TLS handshake completes, applications that need to gather information about the negotiated parameters (cipher suite, curve/group, protocol version) and the handshake timing must call a…

The task

**Problem** Currently, after a TLS handshake completes, applications that need to gather information about the negotiated parameters (cipher suite, curve/group, protocol version) and the handshake timing must call a series of individual “getter” APIs on the `s2n_connection`. This is cumbersome and error‑prone, and it…

Part of Lego-X/LegoFlow-SWE.