Editor State Rules

editor/ owns transient app/editor state types and the app store.
Transient state includes viewport/camera, selection, tools, active entities, and drag/session state.
Do not put persisted document fields here; use core/ for saved image document state.
Do not import React, renderer/WebGL, storage, network, or filesystem APIs.
The store must expose read/subscribe and command dispatch only; no public direct setters.
State changes must flow through commands, including viewport/camera changes.