refactor(ChatScreen): update text colors for dark mode compatibility

- Modified text color styles in SegmentRenderer and styles.ts to utilize theme colors for better adaptability in dark mode.
- Updated bubble colors in palettes.ts to enhance visual consistency across chat components.

src/theme/palettes.ts

@@ -168,8 +168,8 @@ export const darkColors = {
     link: '#5AC8FA',
     success: '#32D74B',
     danger: '#FF453A',
-    bubbleOutgoing: '#3A3A3C',
-    bubbleIncoming: '#2C2C2E',
+    bubbleOutgoing: '#2E5A8C',  // 暗色模式：深蓝气泡
+    bubbleIncoming: '#2C2C2E',  // 暗色模式：灰色气泡
     replyTint: '#1A3A52',
     replyTintActive: '#224060',
     replyBorder: '#4A88C7',