Add an example showing how to customize the Roast logger

[juniper-shopify]

This just works out of the box. We don't need to build anything special to allow people to customize or extend the way the logger works 😃

[juniper-shopify]

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• Add a test utility for mocking CommandRunner execution and an actuall working test case for the simple_agent.rb example #812
• Mark cli e2e tests as slow #811
• Add an example showing how to customize the Roast logger #810 👈 (View in Graphite)
• Hook up some basic logging for cog/workflow begin and end #809
• Add pastel gem for coloured terminal output #808
• Add basic support for Claude 'thinking' messages #807
• Raise a failure when claude message contains the 'error' field #806
• Ignore more Claude message fields #805
• main

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