Discourse Colour Plugin
My suggestion is rather simple and based around the actual forum software itself. There is a plugin on Discourse that would allow you to type in colour. An example of the format will be posted below, but I think this would be great for threads that need that extra splash, especially the likes of admin posts, pinned threads etc.
[color=red]This would be red[/color]
This formatting would also work with HEX codes.
[color=FF0000]This would be red in HEX[/color]