DeepSeek Harness Plugin: Automatic Fallback When Image Attachments Exceed the Limit

This plugin aims to address the issue where DSH's strict admission rules (long side > 2000px and single image > 3.5MB) block users from uploading original phone photos. By intercepting images at the `saveImages` entry point and using sharp to perform automatic fallback processing, it ensures that stored files remain consistently compliant. Core features include aspect-ratio-preserving scaling for oversized images, re-encoding compression, WebP format fallback, skipping animated images, and error resilience. Users can adjust the re-encoding quality via configuration. The plugin resolves conflicts between upstream limits and user behavior, guaranteeing that images processed by downstream systems always remain compliant.