List All Entities for Intercompany JE

Returns ALL entities for intercompany journal entry creation.

This endpoint bypasses entity-scoped filtering because users need to select entities they don't normally have access to when creating intercompany journal entries (per the entity-scoped-user-access spec).

Uses minimal serializer to only expose id, name, and currency - preventing data leakage of sensitive entity details to users who may not have full access to all entities.