`Notebook` now runs over a `Storage` trait: a mounted directory or an SMB share
(`Notebook::open_smb`), so sections and groups are created, renamed, coloured, ordered
and deleted on the share too. The native-compatible SMB client gained file creation,
directory creation, rename (`FileRenameInformation`), delete-on-close and header placement
(`onestore::place` on any `CommitIo`); `smb::tests::live_structure` runs against the Samba
lab VM through `tools/test_smb_structure.py`.

Page copies cover nested tables and paragraph subtrees inside new cells: the place pass
builds tables round by round as their holders appear, and a run's language id is a text
attribute the formatting writer sets. Pages whose indent levels only an outline group can
carry refuse to copy, since the model holds no outline groups. `corpus/page-copy` grows to
seventeen copied pages.

Assisted-by: claude-fable-5.1