Implement PDF export feature with both synchronous and asynchronous modes. Includes:
- New cv-export-server service using Puppeteer
- Shared printable HTML builder module
- ExportControls React component with job status tracking
- Classic template for PDF output
- API endpoints for job management
The system supports cancelable async jobs with polling and error handling. Both client and server share the same HTML rendering logic via the shared-printable module.
