Refactor round 2: fold duplicated command and inspector code

- applyCommands sit on ObjectEditCommand with a revert hook instead of
  five copies of the same preamble and undo
- actionIf replaces six identical Reset/Apply menu blocks, addNameField
  the three name rows, assetLink the two asset links
- requireStructuralObject replaces ten two-line preambles and drops the
  duplicate holder lookup
- __gm.objectsOf had no caller; the SMB remnant in e2e.sh is gone

Proven: check.sh 797 tests, full e2e 633 checks, smokes 24/19/20 against
the same bundle.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/core/commands/sceneObjectCommands.ts

@@ -20,15 +20,15 @@ import {
   requireObjectRef,
   requirePropDef,
   requireHolder,
-  requireStructural,
+  requireStructuralObject,
 } from './require';
 
 /**
  * An edit to one placed object. The base captures the object before the edit and puts it back on
- * undo, so a subclass only says what changes. `applyCommands` deliberately does not use this: its
- * commands carry extra undo state whose restore order matters.
+ * undo, so a subclass only says what changes – and, if it wrote somewhere else too, how to take
+ * that back (`revert`).
  */
-abstract class ObjectEditCommand implements Command {
+export abstract class ObjectEditCommand implements Command {
   abstract readonly label: string;
   private memo: ObjectMemo | undefined;
 
@@ -39,6 +39,8 @@ abstract class ObjectEditCommand implements Command {
 
   protected abstract apply(ref: ObjectRef, project: Project): void;
 
+  protected revert(): void {}
+
   execute(project: Project): void {
     const ref = requireObjectRef(project, this.holderId, this.objectId);
     this.memo = captureObject(ref);
@@ -46,6 +48,7 @@ abstract class ObjectEditCommand implements Command {
   }
 
   undo(): void {
+    this.revert();
     if (this.memo) restoreObject(this.memo);
   }
 }
@@ -71,10 +74,7 @@ export class PlaceAssetCommand implements Command {
     const asset = requireAsset(project, this.assetId);
     const rejection = placementRejection(project, holder, asset);
     if (rejection) throw new CommandError(rejection);
-    if (this.parentId) {
-      requireObject(project, this.holderId, this.parentId);
-      requireStructural(project, holder, this.parentId);
-    }
+    if (this.parentId) requireStructuralObject(project, holder, this.parentId);
     const local = localPositionFor(holder, this.parentId, toPosition(this.position));
     holder.objects.push(createSceneObject(this.objectId, this.assetId, local, this.parentId));
   }
@@ -99,10 +99,7 @@ export class RemoveSceneObjectsCommand implements Command {
 
   execute(project: Project): void {
     const holder = requireHolder(project, this.holderId);
-    for (const id of this.objectIds) {
-      requireStructural(project, holder, id);
-      requireObject(project, this.holderId, id);
-    }
+    for (const id of this.objectIds) requireStructuralObject(project, holder, id);
     this.removed = removeSubtrees(holder, this.objectIds);
   }
 
@@ -226,14 +223,12 @@ export class ReorderObjectCommand implements Command {
 
   execute(project: Project): void {
     const holder = requireHolder(project, this.holderId);
-    requireStructural(project, holder, this.objectId);
-    const object = requireObject(project, this.holderId, this.objectId);
+    const object = requireStructuralObject(project, holder, this.objectId);
     if (this.beforeId === this.objectId)
       throw new CommandError('An object cannot be moved in front of itself');
     let at = holder.objects.length;
     if (this.beforeId) {
-      requireStructural(project, holder, this.beforeId);
-      const before = requireObject(project, this.holderId, this.beforeId);
+      const before = requireStructuralObject(project, holder, this.beforeId);
       if (before.parentId !== object.parentId)
         throw new CommandError('An object can only be reordered among its own siblings');
       at = holder.objects.indexOf(before);
@@ -271,12 +266,10 @@ export class SetParentCommand implements Command {
 
   execute(project: Project): void {
     const holder = requireHolder(project, this.holderId);
-    requireStructural(project, holder, this.objectId);
-    const object = requireObject(project, this.holderId, this.objectId);
+    const object = requireStructuralObject(project, holder, this.objectId);
     if (this.parentId) {
       if (this.parentId === this.objectId) throw new CommandError('An object cannot be its own parent');
-      requireStructural(project, holder, this.parentId);
-      if (isLiveInstance(project, holder, requireObject(project, this.holderId, this.parentId)))
+      if (isLiveInstance(project, holder, requireStructuralObject(project, holder, this.parentId)))
         throw new CommandError('A placed container shows its template; unpack it to put objects inside');
       if (isSelfOrAncestor(holder, this.objectId, this.parentId))
         throw new CommandError('An object cannot be parented to one of its own children');