refactor(engine): move session::snapshot_types to the crate root as snapshot

crates/engine/src/lib.rs

@@ -21,6 +21,7 @@ pub mod recovery;
 pub mod ribbon;
 pub mod sample;
 mod session;
+pub(crate) mod snapshot;
 pub mod speech;
 pub(crate) mod view;
 

crates/engine/src/session.rs

@@ -6,7 +6,7 @@ use serde_json::Value;
 use wordcraft_doc::edit::Fragment;
 use wordcraft_doc::props::CharProps;
 use wordcraft_doc::{Document, PartKind, Path, Pos, StoryRef};
-use wordcraft_layout::{DocLayout, LayoutCache, LayoutOptions, NumeralMode, ViewMode};
+use wordcraft_layout::{DocLayout, LayoutCache, LayoutOptions, ViewMode};
 
 use crate::{CmdError, ImeEditOutcome, Registry};
 
@@ -23,11 +23,11 @@ mod lifecycle;
 mod query;
 mod run;
 mod snapshot;
-mod snapshot_types;
 
 use crate::doc_state;
 use crate::locale;
 use crate::prefs;
+use crate::snapshot as snapshot_types;
 use crate::view;
 pub(crate) use doc_state::Widened;
 pub use doc_state::{CellRange, ColumnBlock, FindState, MathEdit, Selection, UNDO_LIST_MAX, next_math_session};

crates/engine/src/snapshot.rs

@@ -1,5 +1,8 @@
-use super::doc_state::{ColumnBlock, Selection, Undo};
-use super::*;
+use crate::doc_state::{ColumnBlock, Selection, Undo};
+use std::sync::Arc;
+
+use wordcraft_doc::Document;
+use wordcraft_layout::{DocLayout, NumeralMode, ViewMode};
 
 /// What [`Session::restore`] needs to take commands back exactly: the document, the selection,
 /// the undo and redo stacks (also the oldest undo steps the undo limit pushes out meanwhile), the