Moves FileViewer, EditorModal, ConfirmDeleteModal, ToastNotice, MdItemList,
ScopeBadge, and the shared atoms (Empty/SkeletonRows/CopyButton/formatBytes)
into client/src/components/config/ so the upcoming Codex config panel can
reuse them. EditorModal now takes a fetchContent callback instead of calling
api.ccConfig.file itself; CcConfig.tsx supplies the Claude-specific fetcher.
The moved EditorState/ConfirmDeleteState type field widens from
CcArtifactType to string so non-Claude callers can use them too, with a cast
at the two remaining Claude-specific call sites in CcConfig.tsx.
