Cleanup color compute

[natoverse]

• Refactors color compute for better modularity and documentation. Includes removing the ColorMaker class in favor of a single function.
• Parameterizes all scheme compute constants so we can expose deep customization
• Improves public API consistency
• Improves the Vega API and mapping
• Updates the color matching function
• Adds better default params along with validation
• Adds a rainbow scale option
• Adds option to mix a hue into greyscales
• Adds option to tune the scale intensity
• Reserves the accent color for primary charts, excluding it from nominal scales
• Updates the webapp layout a bit to remove header clutter

[dayesouza]

The updates are great! Just one comment that we talked about the cache being removed and the sliders freezing a little but it only happens when the graph visualization is open