bug: Custom subcircuit appearance is lost when choosing Rename during merge conflict

Problem

When merging a subcircuit with a custom appearance via File -> Merge into project..., if the target project already contains a circuit with the same name and the user resolves the conflict by choosing Rename, the custom appearance is completely lost and resets to the default box shape.

Steps to Reproduce

1. Create a project with a subcircuit Sub that has a custom appearance.
2. In the target project (or a copy), ensure there is also a circuit named Sub.
3. In the target project, select File -> Merge into project... and choose the first file.
4. When prompted with the conflict resolution dialog, choose Rename.
5. Open the renamed merged subcircuit in the target project.

Expected Behavior

The renamed subcircuit preserves its custom appearance.

Actual Behavior

The custom appearance of the renamed subcircuit is lost and reverts to the default shape.

Cause

In LogisimFileActions.java, when a naming conflict is resolved with Rename, a new Circuit instance is created and populated with components and wires, but transferring the custom appearance elements from the source circuit is omitted.