Is programming a website for investing money in artistic projects, some of which may contain something forbidden, considered aiding in sin? And must one refuse to work on it despite the consequences? And what is the ruling on money earned from it?

You are not permitted to work in programming websites that promote films and songs forbidden by Islamic law. This is because it constitutes cooperation in sin and aggression. You must repent from this and abandon this work unless there is an extreme necessity, while diligently striving to find another job. As for the money earned from this work, it is permissible for you, and you are not required to donate it or return it to its owners. Your repentance for it is sufficient. This is based on the opinion of the majority of jurists, who hold that a contract involving assistance in a forbidden act is prohibited but not void.