Keep parsed chat and tool detail content in sync with appearance token changes. Hide font-family controls on native, use One as the default syntax theme, add Swift highlighting, and give Nord a distinct light palette.
- Create packages/highlight with shared Lezer-based syntax highlighting (types, parsers, highlighter, color maps)
- Add syntax highlighting and line numbers to file-pane.tsx with memoized CodeLine component
- Import shared highlight colors in git-diff-pane.tsx instead of local definitions
- Delete duplicated syntax-highlighter.ts from both app and server
- Fix TSX dialect to "ts jsx" (correct per Lezer docs)
