Harden GradebookNG's grade-file import so browser metadata, international names, and ordinary assignment…

Harden GradebookNG's grade-file import so browser metadata, international names, and ordinary assignment…: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). The public import entry point must continue to accept the existing CSV media types ( text/csv , text/plain …