chore: fix all compiler warnings

- cmd_result.rs: remove unused Point3 and Rad imports (SWEEP block)
- scene/mod.rs: remove unused Solid3D struct import
- commands.rs: drop unnecessary `mut` on new_entities (REFCLOSE block)
- refedit.rs: annotate insert_handle with #[allow(dead_code)]

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/cmd_result.rs

@@ -1002,7 +1002,7 @@ impl H7CAD {
                 use crate::scene::truck_tess;
                 use crate::modules::insert::solid3d_cmds::empty_solid3d;
                 use truck_modeling::builder;
-                use truck_modeling::{Point3, Rad, Vector3 as TruckVec3};
+                use truck_modeling::Vector3 as TruckVec3;
 
                 let profile_ent = self.tabs[i].scene.document.get_entity(profile_handle).cloned();
                 let path_ent    = self.tabs[i].scene.document.get_entity(path_handle).cloned();

src/app/commands.rs

@@ -1624,7 +1624,7 @@ impl H7CAD {
                 self.push_undo_snapshot(i, "REFCLOSE");
 
                 // Collect the edited temp entities.
-                let mut new_entities: Vec<acadrust::EntityType> = session.temp_handles
+                let new_entities: Vec<acadrust::EntityType> = session.temp_handles
                     .iter()
                     .filter_map(|h| self.tabs[i].scene.document.get_entity(*h).cloned())
                     .collect();