[Accessibility] Input cursor color is hardcoded purple/violet, low contrast, not user-configurable

Environment

• OS: macOS
• Terminal: Warp
• Claude Code version: 2.1.289

Problem
The cursor in the Claude Code TUI input box is rendered in a hardcoded purple/violet color. This color has insufficient contrast against the dark backgrounds commonly used in terminal themes, making it difficult to locate the cursor during input.

Root cause
Claude Code sends ANSI escape sequences that override the terminal emulator's cursor color setting. This means:

• Terminal-level cursor color customization (e.g., via Warp theme cursor_color) is overridden
• Claude Code settings (~/.claude/settings.json) expose no cursor color option
• The Claude Code plugin API exposes no cursor color hook
• There is no supported mechanism for users to change this color

Expected behavior
The cursor color should either:

1. Respect the terminal emulator's configured cursor color, OR
2. Be user-configurable via settings.json

Accessibility impact
Low-contrast cursors are a WCAG 2.1 failure (Success Criterion 1.4.11 — Non-text Contrast requires a 3:1 ratio against adjacent colors). Users who rely on high cursor visibility (low vision, high ambient light, dark themes) are directly impacted.

Suggested fix
Add a cursor_color field to settings.json and use it to set the cursor color via the appropriate ANSI escape sequence (\033]12;<color>\007) at startup and after terminal resets.