[FEATURE] Native VSCode extension: customizable background color for user messages

What feature would you like?

In the native VSCode extension chat panel, allow giving the user's own messages a distinct background color so they're easy to spot when scrolling back through a long conversation.

Current behavior

• In the terminal CLI (fullscreen rendering mode), the userMessageBackground theme token (set via a custom theme in ~/.claude/themes/) colors the background behind user messages. See https://code.claude.com/docs/en/terminal-config.md
• The native VSCode extension has no equivalent: the chat panel's message styling appears hardcoded and does not honor ~/.claude/themes/ custom themes, and there is no extension setting (claudeCode.*) or VSCode colorCustomizations hook for it.

Request

Have the native extension webview honor userMessageBackground (and the related message-background tokens) from custom themes, or expose a setting to give user messages a distinct background.

Use case

Quickly locating my own prompts when scanning the conversation history. The "Session history" feature searches between sessions, not within the current conversation, so a visual marker on my own turns would help a lot.

Environment

• Claude Code v2.1.167, native VSCode extension on Windows 11.