release(v4.12.0): update skill with in-place install and an update admission gate; resume starts the monitor (Issue #72) - archive the review reports, bump the lockstep version

The update skill joins the version matrix and the lockstep test's skill list.

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

.agents/skills/multi-agent-mux-monitor/SKILL.md

@@ -1,7 +1,7 @@
 ---
 name: multi-agent-mux-monitor
 description: "Run a long-lived reconciler that watches .mam/agent-sessions.yaml against the actual herdr/agent runtime state and reconciles them. Use when you want live visibility into which agent sessions are running, which are dead, which have stale YAML entries, and which have new session ids that haven't been recorded yet. Runs as a persistent loop (`reconcile.sh --subscribe`) that keeps going until it times out, idles out, or is interrupted."
-version: 4.11.0
+version: 4.12.0
 author: godopu
 license: MIT
 platforms: [linux, macos]