fix(dimension): keep picture placement consistent with world-space edits

#1681 places a dimension's picture block by its insertion point, rotation
and scale. Edits (move/rotate/scale/mirror, copy, paste) transform the
picture's sub-entities in world space, and the codec's dimension transform
moves the insertion point too, so a rotated or copied dimension would get
the placement applied twice. Fold the placement into the subs before the
edit and leave the dimension at the identity placement afterwards.

The picture insert no longer takes the dimension's extrusion: OCS bakes
picture sub-entities in world coordinates, so only the stored insertion
point goes through the OCS. A zero insertion-scale component counts as 1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/command_driver/clipboard.rs

@@ -512,9 +512,11 @@ pub(crate) fn paste_entities_kernel(
         .iter()
         .cloned()
         .map(|mut entity| {
+            let picture_placement = crate::scene::render_graph::dim_picture_placement(&entity);
             if let Some(t) = translate {
                 crate::scene::view::dispatch::apply_transform(&mut entity, t);
             }
+            crate::scene::render_graph::clear_dim_picture_placement(&mut entity);
             // Same `*D`-block re-point as `finalize_paste` (#290, #161): the
             // baked dimension geometry lives in WCS, so the paste gets its own
             // transformed copy of the snapshotted block.
@@ -527,6 +529,12 @@ pub(crate) fn paste_entities_kernel(
                         .find(|b| b.name.eq_ignore_ascii_case(&bn))
                         .map(|def| def.entities.clone())
                     {
+                        let mut subs = subs;
+                        if let Some(placement) = &picture_placement {
+                            for sub in &mut subs {
+                                crate::scene::view::dispatch::apply_transform(sub, placement);
+                            }
+                        }
                         let bt = translate.cloned().unwrap_or(
                             crate::command::EntityTransform::Translate(glam::DVec3::ZERO),
                         );