feat: enhance article import functionality with reference management

Implement Supabase Storage integration for import files, allowing uploads and downloads of article and price data. Update import processing to utilize the new storage service, including metadata handling and error management. Refactor related services and repositories, and enhance documentation to reflect these changes. Add tests for new functionality and ensure existing tests are updated accordingly.

Enhance article import process by adding support for optional logistic fields (`moq`, `origin`) and implementing progress tracking with `total_rows` and `rows_processed`. Update related schemas, repositories, and services to accommodate these changes. Improve documentation to reflect new features and usage. Add tests for new functionality and ensure existing tests cover the updated logic.

Add article import functionality with CSV and Excel support, including API endpoints for starting imports, listing imports, and handling import errors. Implement background processing for imports, validation, and error handling. Update requirements and documentation accordingly.