Add Codex CLI plugin manifest

[internet-dot]

I opened this as a small metadata pass for the Codex plugin surface in the repo.

A couple of repo-specific details I checked first:

• This is an MCP server that runs and exposes a language server to LLMs. Not a language server for MCP, whatever that would be
• Configure your MCP client: follow one of the guides below
• Configure your MCP client : This will be different but similar for each client. For Claude Desktop, add the following to ~/Library/Application\ Support/Claude/claude_desktop_config.json

This PR adds the Codex plugin metadata, an .mcp.json starting point, and the scanner workflow.
If you want different command wiring or manifest metadata, I can adjust the branch.