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.

.agents/skills/upgrading-expo/references/new-architecture.md

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+# New Architecture
+
+The New Architecture is enabled by default in Expo SDK 53+. It replaces the legacy bridge with a faster, synchronous communication layer between JavaScript and native code.
+
+## Documentation
+
+Full guide: https://docs.expo.dev/guides/new-architecture/
+
+## What Changed
+
+- **JSI (JavaScript Interface)** — Direct synchronous calls between JS and native
+- **Fabric** — New rendering system with concurrent features
+- **TurboModules** — Lazy-loaded native modules with type safety
+
+## SDK Compatibility
+
+| SDK Version | New Architecture Status |
+| ----------- | ----------------------- |
+| SDK 53+     | Enabled by default      |
+| SDK 52      | Opt-in via app.json     |
+| SDK 51-     | Experimental            |
+
+## Configuration
+
+New Architecture is enabled by default. To explicitly disable (not recommended):
+
+```json
+{
+  "expo": {
+    "newArchEnabled": false
+  }
+}
+```
+
+## Expo Go
+
+Expo Go only supports the New Architecture as of SDK 53. Apps using the old architecture must use development builds.
+
+## Common Migration Issues
+
+### Native Module Compatibility
+
+Some older native modules may not support the New Architecture. Check:
+
+1. Module documentation for New Architecture support
+2. GitHub issues for compatibility discussions
+3. Consider alternatives if module is unmaintained
+
+### Reanimated
+
+React Native Reanimated requires `react-native-worklets` in SDK 54+:
+
+```bash
+npx expo install react-native-worklets
+```
+
+### Layout Animations
+
+Some layout animations behave differently. Test thoroughly after upgrading.
+
+## Verifying New Architecture
+
+Check if New Architecture is active:
+
+```tsx
+import { Platform } from "react-native";
+
+// Returns true if Fabric is enabled
+const isNewArch = global._IS_FABRIC !== undefined;
+```
+
+Verify from the command line if the currently running app uses the New Architecture: `bunx xcobra expo eval "_IS_FABRIC"` -> `true`
+
+## Troubleshooting
+
+1. **Clear caches** — `npx expo start --clear`
+2. **Clean prebuild** — `npx expo prebuild --clean`
+3. **Check native modules** — Ensure all dependencies support New Architecture
+4. **Review console warnings** — Legacy modules log compatibility warnings