- Use PNG format instead of JPEG for transparency support
- Non-strict mode only resizes if image width > target width
- Replace CATALOGUE_BACKGROUND_IMAGES_COLOR with CATALOGUE_BACKGROUND_IMAGES_RGBA (tuple default (0,0,0,0))
- Move all inline imports to top of test file
- Add test_resize_non_strict_no_upscale test case
- Add comment explaining settings.DEBUG guard for media serving