Add PostCSS configuration and skills lock file

- Created a new PostCSS configuration file to integrate Tailwind CSS.
- Added a skills lock file containing various Expo skills with their respective source and computed hashes.

index.js

@@ -1,8 +1 @@
-import { registerRootComponent } from 'expo';
-
-import App from './App';
-
-// registerRootComponent calls AppRegistry.registerComponent('main', () => App);
-// It also ensures that whether you load the app in Expo Go or in a native build,
-// the environment is set up appropriately
-registerRootComponent(App);
+import 'expo-router/entry';