What is the ruling on moving trees next to the mosque for the purpose of expansion and creating a shade for worshipers, knowing that they will be moved to a spot adjacent to the mosque, and what if they die during or after the نقل (translocation)?

The one in charge of the mosque's affairs should do everything that entails a benefit for the mosque, and this includes relocating trees around it for the worshippers' benefit. There is no blame if the trees die due to their relocation, provided the intention was reform and not destruction.