Neku Engine v1.0.2 — cheatsheet fix + local sessions

Fixes the Neku Cheatsheet softlock by adding robust close paths and explicit hidden-state CSS. Adds per-client/session local storage so autosave, recents, themes, plugins, layouts, and co-op defaults are scoped to each Studio session. Rebuilt macOS/Windows/Linux Studio zips, sample exports, and GitHub Pages: https://deviverr.github.io/NEKU-Engine/editor/