fix(paste): pasted entities land in the current space

The paste kernel added every entity to model space. It now takes the
space a new entity goes to: the block being edited, a layout's paper
space when no viewport is active, or model space.

Fixes #1652

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/app/command_driver/mod.rs

@@ -95,7 +95,7 @@ mod constraint;
 mod dim_edit;
 
 pub(crate) use clipboard::{
-    copy_to_clipboard_kernel, paste_entities_kernel, remap_ext_subtree_reference,
+    copy_to_clipboard_kernel, paste_entities_kernel, remap_ext_subtree_reference, PasteSpace,
 };
 
 impl OpenCADStudio {