ci: smoke test installed console script

[CoderDeltaLAN]

Summary

• Adds a GitHub Actions smoke step for the installed agent-rules-kit console script.
• Verifies agent-rules-kit --version.
• Verifies a minimal installed-package check --format json command against the single-agent fixture.
• Records the CI hardening change in CHANGELOG.md.

Verification

• Local installed package smoke simulation passed.
• ./scripts/check.sh passed in a temporary dev environment.
• Current local check output: 106 tests, Ruff, text hygiene, and git whitespace checks passed.