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

README.md

@@ -2,7 +2,7 @@
 
 An advanced, high-reliability **Multi-Agent Orchestration & Messaging Backplane** framework built on Herdr and MQTT. It is designed to coordinate, isolate, and audit long-running agent tasks (such as code generation, refactoring, and security reviews) across multiple LLM backend clients (`claude`, `agy`, `hermes`, `grok`, `opencode`, `codex`).
 
-[![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)
 
 ---