Add a native Qt "Bigscreen" shell: CMakeLists, C++ entry (main.cpp, InputRouter), QML module (Theme, ShellWindow, views and components) and a Bigscreen/.gitignore; update top-level .gitignore and README with Qt build/run instructions. Remove the legacy Tauri/web prototype files (package.json, package-lock.json, src-tauri and many web assets) as part of the migration to the Qt/CMake-based shell.
Initialize the Nebula OS Tauri project: add frontend (src/) with HTML, JS, CSS and SVG assets, plus a sample greet UI. Add src-tauri Rust backend (Cargo.toml, build.rs, main/lib) with a greeting command, tauri.conf.json, capability schema and platform icons. Add package.json (dev dependency on @tauri-apps/cli), .gitignore files and VSCode recommended extensions. Expand README with project vision, architecture and phase roadmap to document the Windows-first development plan.
andrew