Feature request: configurable chat colors for user messages in Codex Desktop

Feature request

Please add configurable chat appearance options in Codex Desktop for better readability when reviewing long conversations.

Requested controls

• Different message colors or bubble fills for user vs assistant messages
• Option to customize the user message background color
• Option to customize user/assistant text color
• A high-contrast mode for chat history scanning

Why this matters

When conversations get long, it is hard to quickly find the messages I sent. A distinct visual style for user messages would make conversation review much faster.

Expected behavior

• Default appearance should stay unchanged
• Users can optionally enable custom colors per role
• Changes should apply only to the chat UI, not to code or diff rendering