No 'white' color in the dataset

The xkcd dataset (`color_names.npz`) used for KNN to predict color name from RGB values doesn't has white color.

```
Counter({'black': 1782,
'green': 53000,
'blue': 54785,
'brown': 10529,
'purple': 26416,
'maroon': 3283,
'red': 15476,
'pink': 13617,
'orange': 9152,
'yellow': 7857,
'mustard': 711})
```

In fact, it has only a few colors, not all 27 as mentioned on the [blog post](https://blog.algolia.com/how-we-handled-color-identification/).

> We turned to a K-Nearest-Neighbors algorithm to give color names to RGB values, thanks to the XKCD Color Survey. The XKCD survey consists of 200,000 RGB values labeled with 27 different color names (e.g. black, green, teal, etc.) that we use to train a scikit-learn KNeighborsClassifier.

How do I add white to dataset as I need it.

Inspect color_names.npz and the K-Nearest-Neighbors training or loading entry point to confirm which labels are present and how the dataset is generated. Add or regenerate the missing white examples while preserving the existing label structure, then verify that white appears in the dataset and can be predicted.

Written by the indexing model from the issue text.