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.

metro.config.js

@@ -1,7 +1,11 @@
 // Learn more https://docs.expo.io/guides/customizing-metro
 const { getDefaultConfig } = require('expo/metro-config');
+const { withNativewind } = require('nativewind/metro');
 
 /** @type {import('expo/metro-config').MetroConfig} */
 const config = getDefaultConfig(__dirname);
 
-module.exports = config;
+module.exports = withNativewind(config, {
+  // Keep CSS variables dynamic so PlatformColor and light-dark tokens work correctly.
+  inlineVariables: false,
+});