Print: Print, Print Preview and Print Setup take a print preset by name

file.print, print.preview and print.setup took print settings only as
settings, so an agent had to read a preset with print.presets.list and
copy its settings into the call. They now take preset, the name of
[Default] or of a saved print preset in any case. The preset's settings
are used instead of the document's, settings applies over them, and
print.setup saves them with the document as one undo step. An unknown
name is a parameter error that lists the presets. The app's file.print
with params passes preset on to the engine.

Docs: docs/mcp.md, docs/target-app-parity.md.

crates/engine/src/tests_printpreview.rs

@@ -52,6 +52,20 @@ fn pages_place_the_artboard_on_the_trim_box() {
     }
 }
 
+#[test]
+fn a_print_preset_lays_out_its_settings_with_settings_over_them() {
+    let mut s = Session::new();
+    s.execute("file.new", &json!({"width": 300, "height": 200, "artboards": 4})).unwrap();
+    s.execute("print.setup", &json!({"settings": {"media": "a4"}})).unwrap();
+    s.execute("print.presets.save", &json!({"name": "Sheet", "settings": {"artboards": "range", "range": "4"}})).unwrap();
+    let v = s.execute("print.preview", &json!({"preset": "Sheet", "settings": {"artboards": "range", "range": "3"}})).unwrap();
+    assert_eq!((v["pages"].clone(), v["sheets"][0]["artboard"].clone()), (json!(1), json!(2)), "{v}");
+    assert_eq!(v["settings"]["media"], "letter", "the preset's paper, not the document's");
+    let v = s.execute("print.preview", &json!({"preset": "Sheet"})).unwrap();
+    assert_eq!((v["pages"].clone(), v["sheets"][0]["artboard"].clone()), (json!(1), json!(3)));
+    assert_eq!(s.doc().unwrap().doc.print_setup.as_ref().unwrap()["media"], "a4", "the preview keeps nothing");
+}
+
 /// Point type at (`x`, `y`) in `family` → its id.
 fn type_in(s: &mut Session, x: f64, y: f64, family: &str) -> u64 {
     s.execute("text.create", &json!({"x": x, "y": y, "text": "Ab", "font": family, "style": "Regular"})).unwrap()["id"].as_u64().unwrap()