Paths stored with linked images and placed documents, and the hrefs of
SVG images, go through fileio::document_path (craft-docpath): a relative
path is taken from the document's folder, and only local files or files
on the document's own network share are looked at. Opening a document,
Link Info, Package, the linked-file watch and SVG import all use it; the
watch stats files through fileio, so automation roots apply to it too.
A path that is not followed counts as missing; document.open,
links.check and links.info say why in `refused`.