Commands: view.transparencyGrid lists session as what it writes

The grid is view state of each open document, with no undo step, so its schema's x-writes is session rather than the default document. A test pins x-writes for all six View commands, and the level 1 schema hash is updated.

crates/engine/src/cmd/views.rs

@@ -52,7 +52,8 @@ static TRANSPARENCY_GRID: ParamSchema = ParamSchema::new(
     &[Param::new("on", Type::Boolean).default_note("toggle").null_omitted()],
     "show the transparency grid behind the active document's artboards (each document has its own setting)",
 )
-.returns("{on}");
+.returns("{on}")
+.writes(Writes::Session);
 
 static GLYPH_SNAP: ParamSchema = ParamSchema::new(
     &[