fix(blocks): one base point convention for creation, redefine, insert, explode, XCLIP and REFEDIT

world = insert_point + Rot * Scale * (P - base_point). Attribute placement, EXPLODE, XCLIP storage, REFEDIT's working copy, the UCS reframe of attributes and the dynamic-block visibility grip ignored the base point and were offset by Rot*Scale*base. They now share insert_transform_with_base. Creation stores a ZERO base and redefine resets it; a no-op redefine moves nothing; the Block Definition dialog prefills the base from the definition. XCLIP filters stored by older builds keep their old displacement.

src/app/visibility.rs

@@ -136,7 +136,10 @@ impl OpenCADStudio {
             return;
         };
 
-        let wp = ins.get_transform().apply(Vector3::new(
+        // `def_point` is a block-definition coordinate (see the codec's
+        // BlockVisibilityParameter), so the grip follows the same base-point
+        // convention as the rendered reference.
+        let wp = crate::scene::render_graph::insert_transform(doc, ins).apply(Vector3::new(
             param.def_point.x,
             param.def_point.y,
             param.def_point.z,