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/commands/sheet_set.rs

@@ -2269,8 +2269,8 @@ impl OpenCADStudio {
         let host = self.tabs[i].scene.document.header.insertion_units;
         let k = crate::app::properties::insert_unit_scale(host, units).unwrap_or(1.0);
         let mut insert = codec::entities::Insert::new(name.to_string(), at).with_scale(k, k, k);
-        let transform = insert.get_transform();
         let doc = &self.tabs[i].scene.document;
+        let transform = crate::scene::render_graph::insert_transform(doc, &insert);
         let attdefs: Vec<codec::entities::AttributeDefinition> = doc
             .block_records
             .get(name)