fix(tui): use readable colors for Terminal.app light mode

ANSI "blue" renders as bright purple on light backgrounds.
Use "black" for AI reply text and "gray" for accents on
Terminal.app light mode.

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

packages/cli/src/tui/theme.ts

@@ -96,9 +96,9 @@ const appleTerminalDarkPalette: ThemePalette = {
 };
 
 const appleTerminalLightPalette: ThemePalette = {
-  warmAccent: "yellow",
+  warmAccent: "gray",
   warmMuted: "gray",
-  warmReply: "blue",
+  warmReply: "black",
   warmBorder: "gray",
   statusSuccess: "green",
   statusError: "red",