Save button download the image without the canvas.style being applied.

Steps to reproduce:

- When I click the "Save" button
- My image is downloaded but the colors aren't matching the one from the canvas

Fix:

The bug is located on the [line 53](https://github.com/cyrilf/unique/blob/main/src/lib/components/canvas.svelte#L53) of the canvas component.
To fix it, the color should be applied to the `canvas.fillStyle` instead. We should grab a random color (as we do) and the change the hue only. Using `hsl` color format might help here.