I don't agree with (1), but agree with (2). I recommend just putting a Makefile in the repo and have that have CI targets, which you can then easily call from CI via a simple `make ci-test` or similar. And don't make the Makefiles overcomplicated.
Of course, if you use something else as a task runner, that works as well.
Of course, if you use something else as a task runner, that works as well.