message: frontend/core: fix index import parts
diff: @@ -3,10 +3,10 @@ export {
  default as EntityLink,
  RelativeEntityLink,
  } from './components/EntityLink';
  -export { default as Page } from '../src/layout/Page';
  -export { gradients, theme } from '../src/layout/Page';
  -export { default as Header } from '../src/layout/Header/Header';
  -export { default as HeaderLabel } from '../src/layout/HeaderLabel';
  -export { default as InfoCard } from '../src/layout/InfoCard';
  -export { default as ErrorBoundary } from '../src/layout/ErrorBoundary';
  -export { default as BackstageTheme } from '../src/theme/BackstageTheme';
  +export { default as Page } from './layout/Page';
  +export { gradients, theme } from './layout/Page';
  +export { default as Header } from './layout/Header/Header';
  +export { default as HeaderLabel } from './layout/HeaderLabel';
  +export { default as InfoCard } from './layout/InfoCard';
  +export { default as ErrorBoundary } from './layout/ErrorBoundary';
  +export { default as BackstageTheme } from './theme/BackstageTheme';
  