Add library build pipeline and token alignment report

- Configure Vite library mode to export MUI theme as plain JS
- Add tsconfig.build.json for declaration generation
- Add package.json exports for theme, Tailwind config, and tokens
- Create src/index.ts as library entry point
- Document token alignment between design system and production
  including colour mapping, flagged conflicts, and breakpoint alignment

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/index.ts

@@ -0,0 +1,2 @@
+export { theme } from './theme';
+export type { Theme } from '@mui/material/styles';