feat: cycle view with space

refactor: use baselayer/nglayer to create nehuba config layers
refactor: simplify nglayer obs
feat: restore aux mesh control
chore: remove unused vars in nehubaViewer
refactor: improve viewer_ctx event performance (rather than
emitting all latest events, only emit the relevant event)
bugfix: nehuba.fromRootStore get volume filter when space etc are undefined