Add configurable color for user input in transcript

Problem

When scrolling back through a Claude Code session, it is hard to visually distinguish the commands I typed from Claude's output — everything blends together. In long sessions this makes it slow to locate "what did I last ask?" or "where did I give that instruction?"

Proposed solution

Add a setting to settings.json that lets users style their own typed prompts in the transcript with a color of their choice. The exact color shouldn't be hardcoded by Claude Code — it should be whatever the user picks, since color preferences vary (accessibility, terminal theme, personal taste).

Suggested shape:

{
  "userInputColor": "<any-supported-color>"
}

Accept the standard set of ANSI / named colors (e.g. yellow, cyan, magenta, green, blue, red, white, gray, etc.), and ideally also hex values ("#e5c07b") for users who want to match their terminal theme exactly. Optional modifiers like bold / dim would be a nice extra but aren't required.

Why this is the right shape

• The "auto mode on" indicator in the status line already proves colored accents work well in the UI — extending the same idea to user input would be consistent with what's already there.
• Today there is no workaround:
• statusLine only renders the bottom bar.
• UserPromptSubmit hooks operate at the logic layer and cannot inject ANSI into the transcript.
• Themes only affect Claude's output, not user input.
• Terminal-profile color overrides don't apply because Claude Code renders the transcript itself rather than relying on plain stdin echo.

Impact

• Opt-in (no default change), purely cosmetic, low implementation risk.
• Significant quality-of-life improvement for users with long sessions, accessibility needs, or specific terminal color schemes.

Alternative considered

A fixed color (e.g. always yellow) — rejected, because users have very different terminal backgrounds and color preferences. Making it configurable is only marginally more work and avoids forcing any one choice.