Export / Save SimplyPrint Slicer projects as .3MF#883

It would be very useful to have the option to save/export a SimplyPrint Slicer project as a .3mf file, instead of only being able to keep the project within SimplyPrint or export the sliced G-code.

Our use case is a production environment where we want to use SimplyPrint Slicer as our main slicer. After importing a model and configuring all print/process settings, we need to be able to save that complete setup as a .3mf file.

The exported .3mf should ideally contain:

The original model(s) and their orientation/placement

Process/print settings

Support settings and painted supports, where applicable

Per-object settings/modifiers

Filament/material settings used for the project

Printer/profile information where compatible

This would allow us to archive the exact slicing setup used for an order and reopen or modify it later, either in SimplyPrint or in compatible slicers such as OrcaSlicer/Bambu Studio.

The new Projects functionality in SimplyPrint is already useful for saving projects within SimplyPrint, but being able to export those projects as .3mf would make it much more suitable for professional/production workflows.

For us, this is especially important for traceability: when an order needs to be reproduced months later, we want to retain not just the generated G-code, but the model together with the exact slicing configuration that was used.