release(v4.8.6): Issue #17 item 4 - archive PR #51 reviews and bump the lockstep version

Merge-workspace review: round 1 (@518beda) claude agy grok PASS, codex
NOT PASS (finalize wait measured on the wall clock); fixed in 4c86107.
Round 2 delta (@4c86107) claude agy grok PASS; codex (24b21b9c, after
817d1650 closed deadline_timeout with no report) found R1 closed and no
new defect, but withheld PASS only because its sandbox could not bind
the suite's loopback broker. The same two-file suite run here at
4c86107: 278 passed. Full suite at 518beda on macOS / Python 3.9:
1711 passed / 1 failed / 38 skipped; the failure
(test_issue45_restore, herdr 0.9.3 cwd restore) also fails on main.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VCgu9Fa9iT7TbJUSzdq4Ff

BOOTSTRAP.ko.md

@@ -2,7 +2,7 @@
 
 본 문서는 `herdr_agent_orchestration` 오케스트레이션 및 메시징 백플레인 워크플로우를 새로운 프로젝트에 도입하여 이식하고, 새로운 개발자/에이전트가 초기 가동을 시작할 때 수행해야 하는 환경 설정 및 구축 절차를 안내합니다.
 
-[![Version: v4.8.5](https://img.shields.io/badge/version-v4.8.5-blue.svg)](VERSIONS.md)
+[![Version: v4.8.6](https://img.shields.io/badge/version-v4.8.6-blue.svg)](VERSIONS.md)
 
 새로운 에이전트는 이 안내서에 기술된 절차를 순차적으로 실행하여 초기 환경을 안정적으로 설정할 수 있습니다.