Allow Custom Colors for Frequent Speakers

Problem:

Speaker bubble colors are assigned automatically and the contrast is terrible. Brown on brown is a real thing that happens in nearly every conversation 🤦‍♀️. 

Impact:

Transcripts become hard to read especially when reflecting on a conversation with multiple speakers.

Request:

Let users assign custom bubble colors to speakers they interact with frequently from the Identifying Others page. For anyone without a custom color, keep the random assignment as a fallback.