File viewer/editor pane: no syntax highlighting for Dart/Java (or any language)

Description

The embedded file viewer/editor pane (shown when Claude Code opens/reads a file for the user) renders code with no syntax highlighting at all — everything is a single flat color, no colors for keywords, strings, comments, types, etc.

Steps to reproduce

1. Open a .dart or .java file via Claude Code's file viewer pane.
2. Observe the code is rendered in plain monochrome text — no syntax coloring.

Expected

Standard syntax highlighting (keywords, strings, comments, literals, types) matching the file's language, similar to any modern code editor/viewer.

Affected languages observed

• Dart
• Java

Likely affects other languages too — issue appears to be highlighting not being applied/loaded rather than a per-language gap.