feat: add OpenCode/Codex outputs and update changelog (#104)

* Add OpenCode converter coverage and specs

* Add Codex target support and spec docs

* Generate Codex command skills and refresh spec docs

* Add global Codex install path

* fix: harden plugin path loading and codex descriptions

* feat: ensure codex agents block on convert/install

* docs: clarify target branch usage for review

* chore: prep npm package metadata and release notes

* docs: mention opencode and codex in changelog

* docs: update CLI usage and remove stale todos

* feat: install from GitHub with global outputs

tests/fixtures/sample-plugin/agents/agent-one.md

@@ -0,0 +1,10 @@
+---
+name: repo-research-analyst
+description: Research repository structure and conventions
+capabilities:
+  - "Capability A"
+  - "Capability B"
+model: inherit
+---
+
+Repo research analyst body.

tests/fixtures/sample-plugin/agents/security-reviewer.md

@@ -0,0 +1,7 @@
+---
+name: security-sentinel
+description: Security audits and vulnerability assessments
+model: claude-sonnet-4-20250514
+---
+
+Security sentinel body.