feat(plugins): Codex plugin support + Python plugin variant for Claude

- Add 1c-skills-py to .claude-plugin/marketplace.json (→ port-claude-code-py)
- New .agents/plugins/marketplace.json — Codex marketplace with PS + Py plugins
- Templates .github/templates/{codex,claude}-plugin.json.tmpl rendered by CI
- build-ports.yml: generate plugin manifests on port-codex/port-codex-py/port-claude-code-py; Codex version YYYY.M.D+sha7 auto-bumped per push
- README: install instructions for Codex + Py variant for Claude
- .gitignore: narrow .agents/ → .agents/skills/ so the marketplace is tracked

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -26,7 +26,15 @@
 
 ```
 /plugin marketplace add https://github.com/Nikolay-Shirokov/cc-1c-skills
-/plugin install 1c-skills@cc-1c-skills
+/plugin install 1c-skills@cc-1c-skills        # PowerShell (Windows)
+/plugin install 1c-skills-py@cc-1c-skills     # Python (Linux/Mac или если PS недоступен)
+```
+
+Или установите как плагин OpenAI Codex:
+
+```
+codex plugin marketplace add Nikolay-Shirokov/cc-1c-skills
+codex /plugins   # выберите 1c-skills (PowerShell) или 1c-skills-py (Python) и нажмите Install
 ```
 
 Или используйте скрипт установки: