feat: LOFT command — ruled-surface loft through multiple cross-sections

Picks 2+ profile entities (closed or open wires), builds ruled shells
between consecutive pairs via builder::try_wire_homotopy, caps closed
ends with planar faces, and tessellates the result into a Solid3D mesh.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

src/command/mod.rs

@@ -159,6 +159,11 @@ pub enum CmdResult {
         path_handle: Handle,
         color: [f32; 4],
     },
+    /// Loft through a series of profile entities.
+    LoftEntities {
+        handles: Vec<Handle>,
+        color: [f32; 4],
+    },
     /// INSERT landed on a block that has AttributeDefinitions.
     /// The host should look up the attdefs for `block_name` from the document
     /// and call `attreq_set_attdefs()` on the command, then loop on text input.