Clarify source of freight in freight line

[kejne]

Checklist

• [x] I've searched the issue queue to verify this is not a duplicate feature request.
• [x] I've pasted the output of kargo version, if applicable.
• [x] I've pasted logs, if applicable.

Currently on kargo 0.9.1

Proposed Feature

Warehouses should be colored in different colors from stages to avoid confusion of the meaning of the colors in the freight line.

Freight could have a border with the same color as the warehouse to clearly visualize the origin of the freight.

Motivation

When working with multi-warehouse stages, it is very inconvenient to see what should be promoted and what it actually is that is being promoted. Clicking the small filter button on the wanted warehouse is quite tedious. Currently, the only way to see the origin now is to hover over the image in the freight to see the image url.

Suggested Implementation

The color generator should make sure that warehouses always have different colors than stages and freight could be marked with this in some other way than the marks which set the stages.

I would suggest a color scheme for the warehouses that is more subtle, so that they don't scream as much as this picture - but could be a good visualization otherwise.

[krancour]

Colors have been a persistent problem due to the finite number of aesthetically acceptable hues and the surprisingly limited human capacity for distinguishing between similar shades. Owing to this, using separate color palettes for Warehouses (and the Freight they produce) and Stages may not prove possible yet...

But as to the idea of a colored border on Freight in the timeline to provide a better visual cue as to where each piece of Freight came from... that is an excellent suggestion, and should be fairly easily accomplished!