Engine: standard parts fix their sketch's entities through the store (#5425, after #6376)

#6376 (a standard part's sketches are fully defined) reads the sketch being drawn straight from
the document's features, after this branch's base. `fix_all` now takes it from
`sketch_store::active` and `sketch_store::read`, as the store's scan requires, with the same
result.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/parts.rs

@@ -272,10 +272,7 @@ fn revolve(s: &mut Session, pts: &[(f64, f64)], op: &str) -> Result<()> {
 /// Fix every point and curve of the sketch being drawn: a standard part's outline is its size, so
 /// its sketches are fully defined and a check of the design finds nothing left free in them.
 fn fix_all(s: &mut Session) -> Result<()> {
-    let sketch = s.active_sketch.and_then(|id| s.doc.features.iter().find(|f| f.id == id)).and_then(|f| match &f.kind {
-        solidcraft_doc::FeatureKind::Sketch { sketch, .. } => Some(sketch),
-        _ => None,
-    });
+    let sketch = super::sketch_store::active(s).and_then(|id| super::sketch_store::read(&s.doc, id).ok());
     let entities: Vec<String> =
         sketch.map(|sk| sk.points.iter().map(|p| p.id.clone()).chain(sk.curves.iter().map(|c| c.id.clone())).collect()).unwrap_or_default();
     if !entities.is_empty() {