Add a .gitignore and remove numerous @nebulaproject packages and their asset files from node_modules to stop committing dependency artifacts (glyphs, binaries, src/dist files). Also update packages/core/package.json metadata and refresh lockfiles.
Import initial monorepo structure for Nebula Core: add packages (@nebula/core, core-glyphs, core-input, core-navigation, core-theme, core-ui, core-utils) with source, dist, tests and assets. Expand README with overview, quick start and API snippets, and add package-level documentation files. Add jsconfig.json for path mapping, package.json and lockfiles to bootstrap the repo. This commit sets up the project layout, docs, and local package links for further development.
andrew