feat: Convert to Sheet Metal takes a solid or a shelled body by its bend edges (#725)

Convert to Sheet Metal now takes a solid or a shelled body by its bend edges (`bends`): the faces reached from the fixed face across those edges become the sheet, keeping the part's envelope, with the flat pattern by the rule's K-factor and radius. Other edges between sheet faces are cut open. The result works with edge flanges, cuts, Unfold/Refold, the flat pattern and DXF. A conversion without `bends` is the plate conversion as before. The optional `bends` field is noted under format 17. Fixes #647.

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

crates/engine/src/cmd/edit.rs

@@ -342,6 +342,12 @@ fn edit_feature(s: &mut Session, p: &Value) -> Result<Value> {
             nf.edge_names = solidcraft_doc::sheet::sheet_edge_names(&s.model.state_before(id), &points(a));
         }
     }
+    // New bend edges for a conversion: the names of the body's edges there now.
+    if let (FeatureKind::SheetConvert { bends: a, body, .. }, FeatureKind::SheetConvert { bends: b, body: was, .. }) = (&nf.kind, &f.kind)
+        && (a != b || body != was)
+    {
+        nf.edge_names = solidcraft_doc::sheet::bend_edge_names(&s.model.state_before(id), body, a);
+    }
     // Profiles picked by index or point are kept by their curves, as when the feature was made.
     if nf.kind.clone().profile_sels_mut() != f.kind.clone().profile_sels_mut() {
         super::features::stable_profiles(s, &mut nf.kind)?;