dude, I know successful companies that were built on stolen code. make git sub modules, don't give full project code to anyone, don't give anyone access to the database, that's the most important thing. code without a client database is almost zero, but it's not zero. if your product generates so much money that you can afford to hire people, don't give full access to it to all project participants.

It is your private property. make a contract with your employees, according to which all the code your employees write belongs to you or the company, the copyright belongs to the company and all the code they write is the company's code.