fix(tui): adjust theme colors for better contrast

- WARM_ACCENT: #c88a56 → #d4a070 (warmer highlight for ◆ and accents)
- WARM_REPLY: #f0e6d8 → #c0a480 (warm sand tone for AI response body)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/cli/src/tui/theme.ts

@@ -1,6 +1,6 @@
-export const WARM_ACCENT = "#c88a56";
+export const WARM_ACCENT = "#d4a070";
 export const WARM_MUTED = "#8f8374";
-export const WARM_REPLY = "#f0e6d8";
+export const WARM_REPLY = "#c0a480";
 export const WARM_BORDER = "#6b6156";
 
 // Semantic status colors