feat: distribute the CLI Agent Skill as a Codex plugin

[cablate]

Summary

• package the existing Google Maps CLI Agent Skill as a portable, Skill-only plugin
• add a CabLate repo marketplace that installs the published npm package
• keep MCP configuration independent; the plugin invokes the standalone �xec CLI through
  px
• move maintainer-only project knowledge out of the public skills/ directory
• document marketplace installation in English and Traditional Chinese
• keep plugin manifest versions synchronized with automated npm releases

Verification

• plugin-creator validation passed
• Agent Skill archive check passed
• 32/32 unit tests passed
• TypeScript build passed
• npm dry-run package contains both plugin manifests and only the public Google Maps Skill