fix: keep exact snapping, source drawing data and adaptive options layout

Resolve curve intersections through cadkernel, retain empty exact results, gather analytic candidates independently of tessellation, and bound material uploads. Preserve large MINSERT data while limiting rendering work; remove obsolete review narratives.

src/scene/entity.rs

@@ -298,10 +298,6 @@ impl Scene {
         };
 
         if !handle.is_null() {
-            // New geometry drawn during REFEDIT belongs to the edited block,
-            // so it must stay bright along with the copied block entities.
-            // The remaining model-space entities are only visible as faded
-            // context.
             if let Some(keep) = self.refedit_keep.as_mut() {
                 keep.insert(handle);
             }