- Rename thumb_module.go to thumbnail_module.go and thumb_config.go to thumbnail_config.go
- Update all function names from showThumbView/addThumbSource/etc to showThumbnailView/addThumbnailSource/etc
- Update all struct fields from thumbFile/thumbFiles/etc to thumbnailFile/thumbnailFiles/etc
- Update config struct from thumbConfig to thumbnailConfig
- Update job type from JobTypeThumb to JobTypeThumbnail
- Update module registration from 'thumb' to 'thumbnail' in main.go
- Update UI components to show 'THUMBNAIL' instead of 'THUMB'
- Update handler function from HandleThumb to HandleThumbnail
- Update file naming patterns from 'thumb_*.jpg' to 'thumbnail_*.jpg'
- Update author module references to use Thumbnail naming
- Update documentation in QUEUE_SYSTEM_GUIDE.md
- Maintains all existing functionality while using clearer naming
