On your development machine (not the server), do something like:

# One time per machine
git lfs install

# Create a new local repo
mkdir 3d-models
cd 3d-models
git init

# Add Forgejo as remote (adjust user/repo)
git remote add origin https://forgejo.rozic-dev.com/<your_user>/<your_repo>.git
# or use SSH later when we set that up


Now set up LFS for STEP files:

git lfs track "*.step"
git add .gitattributes


Copy one of your 3D models into the folder, e.g. model.step:

cp /path/to/your/model.step ./model.step

git add model.step
git commit -m "Add first STEP model"
git push -u origin main
# if it complains about 'main' not existing, try:
# git push -u origin master


If LFS is working, the .step file in the web UI will look small (Git pointer), and in Repo → Settings → LFS you’ll see actual LFS objects stored.