SingleFile CLI 2.18.1

CLI fixes and improvements

--remove-alternative-images now also decides whether the alternative images are downloaded. On, only the displayed image of an <img> or <picture> is requested. Off, the srcset variants are downloaded and kept with their media queries and sizes, so the saved page stays responsive. --block-alternative-images is deprecated and accepted as an alias: it defaulted to on, so turning --remove-alternative-images off used to leave empty <source> elements in the saved page instead of the variants.
The Docker image build waits for the npm tarball of the released version before installing it.
Updated single-file-core to 1.6.28.

Co-authored by Claude (Claude Code)