Permanent IDs for API usage

[JulianVennen]

Is your feature request related to a problem?

Currently, the only thing that identifies a project in the Hangar API is the project's slug, but this slug can be changed by the plugin authors.
In many cases, API users want to keep tracking the same project even if the slug changes. This is currently not possible.

Describe the solution you'd like.

The project ID should be exposed to the API, and it should be possible to use endpoints with the project ID instead of the slug.

Describe alternatives you've considered.

Alternatively, you could remove the option to change the slug of a project, but if authors really want to change their slug they might create a new project instead.

Other

No response