Preserve ECH acceptance in uTLS connection state

[wy15]

Summary

Preserve ECHAccepted when adapting a uTLS QUIC connection state to the standard-library tls.ConnectionState used by quic-go.

Why

Hysteria v2.12.0 enables ChromeParrot by default. Its client passes a configured ECH config list into uTLS, but the ChromeParrot adapter omitted ECHAccepted while translating the resulting connection state. The omitted boolean therefore remained false, causing Hysteria's successful connection log to report "ech": false even when the server accepted ECH.

This was reproduced with Hysteria v2.12.0 on both client and server: the default ChromeParrot path logged "ech": false, while setting quic.disableChromeParrot: true made the same ECH configuration log "ech": true.

Changes

• Copy s.ECHAccepted into the standard-library connection state.
• Add a focused regression test for the uTLS-to-standard-library state conversion.

Validation

go test ./internal/handshake -run TestUTLSConnectionStateToStdPreservesECHAccepted -count=1
go test ./internal/handshake -count=1

Both checks pass.