feat: add routing with MainPage (full-screen 3D) and DetailsPage

- Add react-router-dom for routing
- Create MainPage with full-screen 3D demo viewport
- Create DetailsPage with all existing documentation blocks
- Create demoPlaylist.ts with 8 showcase cases
- Add styles for main page HUD, controls, progress bar
- Routes: / → MainPage, /details → DetailsPage, * → redirect to /

package.json

@@ -15,6 +15,7 @@
     "@vitejs/plugin-react": "latest",
     "react": "latest",
     "react-dom": "latest",
+    "react-router-dom": "^7.18.1",
     "three": "^0.185.1",
     "typescript": "latest",
     "vite": "latest"