- Fix authentication header from 'Bearer' to 'Token' (DRF TokenAuth)
- Implement three-strategy upload system:
1. URL pass-through for direct URLs (most efficient)
2. Base64 data URL conversion for screenshots
3. Fallback blob upload for any other format
- Add comprehensive error handling with response details
- Add detailed logging for debugging upload strategies
- Document thumbnail formats in extractThumbnailStealth()
Fixes#30 - Tandoor image upload 400 Bad Request error
Based on Tandoor source code analysis (cookbook/views/api.py):
- RecipeImageSerializer accepts 'image_url' field for server-side download
- Uses Token authentication, not Bearer
- Supports multipart file upload with proper MIME types
