Guides: Shift selects ruler guides and art together

A Shift-click on a guide adds it to the selected art (guide.select
toggle keeps the art), and Shift-adding or -removing art keeps the
selected guides; a new selection still clears them. With both selected,
Delete deletes the art and the guides in one undo step (not when ids are
given).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CC5DiGJEZ5ADaQMBEQk4W1

crates/engine/src/cmd/edit.rs

@@ -268,6 +268,8 @@ fn clear(s: &mut Session, p: &Value) -> Result<Value> {
         return super::docmenu::guide_remove(s, &json!({}));
     }
     let st = s.doc()?;
+    // Guides selected with the art go with it (not when ids are given).
+    let with_guides = explicit.is_none();
     let targets = explicit.unwrap_or_else(|| st.selection.in_paint_order(&st.doc));
     // Keep the selected ids themselves, without promoting compound members. Delete a selected
     // ancestor just once; its selected descendants leave with it. Layers themselves are kept.
@@ -284,6 +286,10 @@ fn clear(s: &mut Session, p: &Value) -> Result<Value> {
         for id in &ids {
             d.remove(*id)?;
         }
+        if with_guides {
+            let gone = sel.guides.clone();
+            d.retain_guides(sel, |i, _| !gone.contains(&i));
+        }
         sel.clear();
         Ok(())
     })?;