Exclude Ninja from init command

[NiklasBuchfink]

Context

• Ninja does not work without lint rules
• Fink Standalone is not linkable as long as there is no host

Proposal

With the release of ParaglideJS with SDK2, it makes no sense to recommend Ninja with it anymore.

Optional: A warning for existing projects to inform them in the console/migration guide that the new format is incompatible with Ninja