RxD Fix

[ejohnstown]

1. Forwarding fixes in echoserver. (Really a general channel issue.)
2. Agent fixes in echoserver.

[Copilot]

Pull request overview

Fixes handling around “channel RX’d” (WS_CHAN_RXD) and agent setup paths, primarily to improve forwarding behavior in the echoserver and make agent-related code compile cleanly.

Changes:

• Treat WS_CHAN_RXD as a successful outcome for returning lastRxId from wolfSSH_worker().
• Silence unused-parameter warnings in agent stubs.
• Fix echoserver agent UNIX-socket setup flow so it proceeds correctly after snprintf() and simplifies the socket() error assignment.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/ssh.c	Returns channelId not only on WS_SUCCESS but also on WS_CHAN_RXD so callers can identify the channel that received data.
src/agent.c	Adds WOLFSSH_UNUSED(agent) to avoid unused-parameter warnings when logging is compiled out.
examples/echoserver/echoserver.c	Corrects agent local setup flow after snprintf() and adjusts UNIX-socket bind/setup logic.

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[Copilot]

If socket() succeeds but bind()/setenv()/listen() fails, the code returns an error without closing ctx->listenFd or removing any partially-created UNIX socket path/env var. Since the agent callback return value is not always checked by the library, this can leak FDs and leave stale /tmp/wolfserver. sockets on failure. Consider adding an error-cleanup path that closes ctx->listenFd (and unlinks/unsets as applicable) before returning.