Pages drag to a new place in their section, and swipe or the context menu
makes one a subpage or promotes it; Move to Section, or a drop on a section
in the sidebar, moves one to another section, as the desktop moves a page
dropped on a section tab. Sections and groups drag within their notebook or
into a group, or go through Move; notebooks drag within their place in the
list, which keeps the order. Edit shows reorder handles, and VoiceOver offers
Move Up, Move Down, Make Subpage, Promote Subpage and Move as actions.

Each move is the desktop's edit through crates/mobile: sb_section_arrange
applies notebook::session::arrange, now shared with the desktop's Undo, as one
revision; sb_library_move_page imports the page into the other section and
deletes it from its own; sb_library_place moves and orders TOC entries with
Notebook::move_entry and reorder. Undo and Redo (shake, three-finger swipe,
Command-Z in a list) take each move back the same way.

Assisted-by: claude-opus-5.5