✨ Create a template repo for Blake site templates

[matt-goldman]

Create a new template repository for users to create Blake site templates easily. This template repo should:

• Start from a base Blake site, with Blake already fully configured.
• Be essentially the starter site generated by running blake new with no parameters, including sample content for demonstration.
• Be pre-configured to integrate with the workflow for testing and merging site templates into the registry, once that workflow is implemented.
• Serve as a starting point for users to develop and contribute new Blake site templates.

Note: This work should be started after the workflow for testing and merging site templates into the registry is complete, and should be wired up to hook into that workflow.