Bootstrap NebulaOS repo and desktop shell UI

Initialize the NebulaOS monorepo layout with top-level documentation, ignore rules, placeholder service/package directories, compositor docs plus a baseline Sway config, and session startup/desktop entry files. Add the first desktop shell prototype under `shells/desktop/ui` using React + Vite, including themed surface components (desktop, top bar, launcher, preview), mock Nebula APIs and shell bridge state wiring, reusable UI controls/icons, and supporting styles/config needed for local development.

shells/desktop/ui/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "nebula-desktop-ui",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "lint": "oxlint",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "react": "^19.2.8",
+    "react-dom": "^19.2.8"
+  },
+  "devDependencies": {
+    "@types/react": "^19.2.18",
+    "@types/react-dom": "^19.2.4",
+    "@vitejs/plugin-react": "^6.1.0",
+    "oxlint": "^1.79.0",
+    "vite": "^8.2.2"
+  }
+}