Paste where the view shows it, editor offsets included (#263)

Paste mixed two frames. The pointer comes from the Scene View, which
draws every object moved by the editor offsets of it and its parents.
Paste turned that point into a local position through the parents'
plain world transform, so the copy landed beside the pointer by the
offset of the parent it went into. Without a pointer, an original with
an offset of its own had its copy placed beside its game position,
which the view does not show.

- A copied root now remembers where the view showed it
  (`ClipRoot.shown`, from `editorTransform`) instead of its world
  position.
- New `editorLocalPositionFor` in `properties/transform.ts` turns a
  shown point into a local position through the parent chain with the
  editor offsets, as the view draws it. Paste uses it.
- The copy itself still gets no editor offset of its own, as since
  #240. In the game it stands where it was drawn, minus the offsets of
  its parents.
- Re-parenting under a parent with an offset still keeps the game
  position, so the object jumps in the view by that offset. That is a
  different rule from paste and is left as it is.

Tests:
- Unit (clipboard, groups, references, transform): 50 passed, 2 new.
- e2e 51 on melektaus-atx: ALL PASSED, 12 checks, 1 new (51f).
- Gate on melektaus-atx: 195 files, 2829 tests, CHECK EXIT 0.
- Counter-checks: without the paste fix both new unit tests fail
  (copy at 540/470 instead of 500/500) and 51f fails by exactly the
  60/-40 offset. With the root remembering its world position again,
  the own-offset unit test fails.
- No full run. The e2e total of 1591 is 1590 plus 1.

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

src/core/commands/pasteCommands.ts

@@ -11,7 +11,7 @@ import { placementRejection } from '../model/placement';
 import type { Vec2 } from '../model/Properties';
 import { findAsset, type Project } from '../model/Project';
 import type { SceneObject } from '../model/SceneObject';
-import { carryTransform, localPositionFor, parentTransform } from '../properties/transform';
+import { carryTransform, editorLocalPositionFor, parentTransform } from '../properties/transform';
 import { type Command, CommandError } from './Command';
 import { requireGraph, requireHolder, requireNodeDef, requireStructuralObject } from './require';
 
@@ -22,8 +22,8 @@ function freshIds(ids: readonly string[]): Map<string, string> {
 
 /**
  * Puts copied objects into a scene or container (#240). Each root goes under the parent `parents`
- * names for it ('' or missing = top level), shifted by `shift` in world units, and keeps its look
- * the way a re-parent does.
+ * names for it ('' or missing = top level), shifted by `shift` from where the editor showed it, and
+ * keeps its look the way a re-parent does.
  */
 export class PasteObjectsCommand implements Command {
   readonly label: string;
@@ -69,10 +69,10 @@ export class PasteObjectsCommand implements Command {
       copy.parentId = parentId;
       // The copy stays in its group when it lands at the top level of a holder that has the group.
       if (parentId || !findGroup(holder, copy.groupId ?? '')) delete copy.groupId;
-      copy.position = localPositionFor(project, holder, parentId, {
-        x: root.world.x + this.shift.x,
-        y: root.world.y + this.shift.y,
-        z: root.world.z,
+      copy.position = editorLocalPositionFor(project, holder, parentId, {
+        x: root.shown.x + this.shift.x,
+        y: root.shown.y + this.shift.y,
+        z: root.shown.z,
       });
       const after = parentTransform(project, holder, parentId).m;
       carryTransform(findAsset(project, object.assetId)!, copy, root.parentMatrix, after);