feat(04-02): add Vite alias to redirect OnboardingWizard to NexusOnboardingWizard

- Alias uses absolute path (path.resolve) for correct Vite import resolution
- [nexus] comment marks the change for rebase visibility
- Original OnboardingWizard.tsx and App.tsx remain unmodified

ui/vite.config.ts

@@ -9,6 +9,9 @@ export default defineConfig({
     alias: {
       "@": path.resolve(__dirname, "./src"),
       lexical: path.resolve(__dirname, "./node_modules/lexical/Lexical.mjs"),
+      // [nexus] Replace upstream OnboardingWizard with Nexus single-step version
+      [path.resolve(__dirname, "src/components/OnboardingWizard")]:
+        path.resolve(__dirname, "./src/components/NexusOnboardingWizard"),
     },
   },
   server: {