Is it permissible for workers in a company, whose homes are far away, to shorten prayers (qasr) and combine them with Friday prayer (Jumu'ah), given that they reside there for a month, then return for another month, knowing that the area is inhabited only by workers and has a mosque and an Imam?

It is not permissible for someone who intends to reside for a month to shorten the prayers during this period, and this is the view of the majority of scholars. Whoever shortens their prayer must make it up in full, unless they were following someone who issued a fatwa permitting it. As for the Friday prayer, it is not valid for non-residents, and they must perform the Dhuhr prayer instead.