tutorial_image_detection.ipynb fails on Windows: Unix-only shell command and missing COCO dataset setup instructions #612

While completing the tutorial_image_detection.ipynb walkthrough on Windows, I hit two issues that block the notebook from running end-to-end out of the box:

1. !mkdir -p is Unix-only

The second cell uses:

!mkdir -p local/data/models
!mkdir -p local/outputs

-p is not a valid flag for Windows cmd.exe (which Jupyter shells out to by default on Windows), so this cell fails with SyntaxError: unexpected character after line continuation character.

2. COCO dataset cell has placeholder paths with no setup guidance

The dataset-loading cell expects:

img_dir = "<PATH_TO_COCO_VAL2017_IMAGES>"
ann_file = "<PATH_TO_COCO_INSTANCES_VAL2017_JSON>"

but there's no instruction anywhere in the notebook on how to obtain COCO val2017 data, so new contributors have no path forward without external research.

Proposed fix

• Replace !mkdir -p with a cross-platform os.makedirs(..., exist_ok=True) call.
• Add a cell (or a linked script) that downloads and extracts COCO val2017 images + annotations automatically, so the notebook is fully runnable without manual dataset hunting.

I've already implemented and tested both fixes locally on Windows and I'm happy to open a PR.