UDS server minor: typo, read vs readn, socklen cast

[jeonghanlee]

Summary

Minor server-path cleanups: the typo "unkonown" in the accept message; the accept loop uses raw read() while con_core uses the EINTR-retrying readn(); int is cast to socklen_t* at accept.

Location

con.cpp:686 (typo), 698 (read vs readn), 679 (cast).

Acceptance

• Fix the typo; use readn consistently; use a socklen_t variable for the accept length.

Verification

• UDS server suite green (no behavior change expected)

Backlog (deferred). Register: docs/milestone.md. Tests land in the release cycle that schedules this.