- Add POST /attachments for secure multi-file upload with validation
- Add GET /attachments for listing transaction attachments
- Add GET /attachments/:id for attachment metadata retrieval
- Add GET /attachments/:id/download for secure file download
- Add DELETE /attachments/:id for soft deletion
- Include comprehensive security validation: file type, size, content detection
- Implement proper error handling and cleanup on failures
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
