Review follow-up on #9975. The help text and the CLI book page said the
XMP and free-form text are kept in every flat export and the ICC profile,
EXIF and resolution "either way". Not every format holds them: JPEG and
WebP have no place for free-form text, TIFF writes only its named text
tags, and an Indexed Color document's palette PNG carries no XMP, text,
ICC or EXIF at all, only its resolution. The texts (and the parity-doc
revision row) now say the XMP and text are kept where the format holds
them and that the option leaves everything else as it is without it.
The test fixture gains a free-form text entry and a Display P3 profile
(from photocraft-cms, now a dev-dependency; no profile file committed),
so it checks the text is gone with `none` and kept by a default PNG, and
that the default export keeps a real ICC profile that `none` matches,
instead of comparing None with None.
ljkx
a99e8696fc