Test examples from docs

docs/assets/screenshots/CLI-k3d.png

docs/assets/screenshots/local_thickness_2d.png

docs/assets/screenshots/synthetic_blob_slices.png

docs/cli.md

qim3d/generate/blob_.py

qim3d/io/loading.py

qim3d/io/saving.py

qim3d/models/unet.py

qim3d/processing/local_thickness_.py

qim3d/processing/mesh.py

qim3d/processing/operations.py

qim3d/viz/colormaps.py

qim3d/viz/explore.py