Install CLI: abstraction over the default install paths

[thomas-bartlett]

Problem

A new CodeGuard user currently picks between rule files, skills, the MCP server, and a per-agent install path before they can get started. Each option is valid for a different audience, but choosing between them requires prior knowledge of what skills and MCP servers are. As we ship more artifacts, that choice gets harder, not easier.

The outcome we want: a user can install CodeGuard with one command and without needing to understand the underlying delivery mechanism.

Proposal

Build a CLI that installs the recommended default for the user's environment and keeps it updated. Position it as the primary entry point in the documentation, with the current per-agent instructions moved behind it as advanced options.

The risk is that the CLI becomes one more option on an already long list. It only works if the docs present it as the default path for anyone who does not have a reason to pick something else.

Open questions

• Is a CLI the right abstraction, or is a uvx codeguard init one-liner enough without introducing a new artifact?
• Distribute via PyPI? That enables uvx and pipx install but adds packaging overhead and raises the bar on release signing (Issue Add release artifact signing #35).
• Scope for a first version: install only, or also update and validate?
• Implementation: Python with Typer and Rich.

[thomas-bartlett]

Moved to #85 for tracking.