Output folders and file layout

Describe the results root structure created by the GUI.

Recommended content:

• how city/experiment identifiers map to folders

• Stage-1 artifacts (NPZ, scalers, manifests)

• Stage-2 artifacts (checkpoints, metrics, exports)

• Transferability artifacts (matrix CSV/JSON, panels)

• Map artifacts (if you export snapshots/figures)

Use code blocks showing typical folder trees.