* fix(irc): prevent ghost nick collisions on rejoin after network delay
* test(irc): add regression tests for fallback nick uniqueness
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---------
Co-authored-by: wendy-chsy <wan.wenyan@xydigit.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>