fix: resolve TypeScript export conflict for Change type

- Separate value export (diffLines) from type export (Change)
- Use 'export type' for Change to avoid declaration conflict
- Fixes compilation error: Export declaration conflicts with exported declaration of 'Change'

The issue was that tsup was generating both an interface declaration and
a type export for Change, causing a TypeScript compilation error.

Author: Tajudeen

src/vs/workbench/contrib/cortexide/browser/react/src/diff/index.tsx

@@ -5,4 +5,5 @@
 
 import { diffLines, Change } from 'diff';
 
-export { diffLines, Change }
+export { diffLines };
+export type { Change };