Build a Backstage scaffolder template with fetch:template and publish:github steps

Steps

1. Define a Template entity in a YAML file with apiVersion: scaffolder.backstage.io/v1beta3 and kind: Template; populate metadata.name and spec.type.
2. Declare spec.parameters as a list of form step objects, each containing a JSON Schema under properties to collect user inputs such as component name and repo owner.
3. In spec.steps, add a step with id: fetch-template, action: fetch:template, and input.url pointing to a skeleton directory in a Git repository; use ${{ parameters.name }} to interpolate user inputs into the skeleton files.
4. Add a subsequent step with action: publish:github and inputs repoUrl, defaultBranch, and description to create the new repository from the rendered skeleton.
5. Optionally add a catalog:register step after publish to automatically register the generated catalog-info.yaml with the Backstage catalog.
6. Register the template YAML itself in the catalog so it appears in the Create page; test end-to-end in a staging Backstage instance before sharing with developers.