[FEATURE] First-party CLI (archunitpy) #39

In short

Right now you can only run ArchUnitPython from inside a pytest test. This adds a terminal command — archunitpy check — plus commands to draw the dependency graph and scaffold a config, so you can check architecture in CI or a pre-commit hook without writing a test.

Problem

ArchUnitPython runs only under pytest today. A CLI lets people run checks and generate graphs/reports from CI one-liners, pre-commit hooks, and ad-hoc exploration without writing a test — the way most Python module-boundary tools are used.

Proposal

Ship a console-script CLI (archunitpy) over the existing engine: archunitpy check (non-zero exit on violations), archunitpy graph, archunitpy report, and archunitpy init to scaffold a config.

Acceptance criteria

• archunitpy check runs configured rules and exits non-zero on violation.
• archunitpy graph --format dot writes a graph via the existing exporter.
• archunitpy init scaffolds a starter config; documented in the README.
• Empty-test protection still applies from the CLI path.