feat(core): Add modelling for pending edits and entity preview

## Goals
Add the ability to query entities after a potential edit was applied so that users can compare the current state of the KG with a potential future state.

The issue describes adding modeling for pending edits and entity previews in a knowledge graph. Look for existing entity and edit models in the codebase, likely in a core module. Understand how entities are currently queried and stored. The goal is to allow comparing current state with a potential future state, so changes may involve query logic, data structures, and possibly a preview API.

Written by the indexing model from the issue text.