Is it obligatory to work full-time as an employee in a shop, or to search for another job that allows for diligent study in computer science and the pursuit of Islamic knowledge?

If you do not need this job to support yourself, then the default is to devote yourself to seeking Islamic knowledge and developing your computer skills to find another job that suits your specialization and allows you to combine it with knowledge. However, if you do need it and can combine it with performing your obligatory duties, then it must be given precedence over acquiring non-obligatory knowledge; because supporting oneself is obligatory, and it is not permissible to prioritize a supererogatory act over an obligatory one. A supererogatory act is not given precedence over an obligatory duty.