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/expo-av-to-audio.md

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+# Migrating from expo-av to expo-audio
+
+## Imports
+
+```tsx
+// Before
+import { Audio } from 'expo-av';
+
+// After
+import { useAudioPlayer, useAudioRecorder, RecordingPresets, AudioModule, setAudioModeAsync } from 'expo-audio';
+```
+
+## Audio Playback
+
+### Before (expo-av)
+
+```tsx
+const [sound, setSound] = useState<Audio.Sound>();
+
+async function playSound() {
+  const { sound } = await Audio.Sound.createAsync(require('./audio.mp3'));
+  setSound(sound);
+  await sound.playAsync();
+}
+
+useEffect(() => {
+  return sound ? () => { sound.unloadAsync(); } : undefined;
+}, [sound]);
+```
+
+### After (expo-audio)
+
+```tsx
+const player = useAudioPlayer(require('./audio.mp3'));
+
+// Play
+player.play();
+```
+
+## Audio Recording
+
+### Before (expo-av)
+
+```tsx
+const [recording, setRecording] = useState<Audio.Recording>();
+
+async function startRecording() {
+  await Audio.requestPermissionsAsync();
+  await Audio.setAudioModeAsync({ allowsRecordingIOS: true, playsInSilentModeIOS: true });
+  const { recording } = await Audio.Recording.createAsync(Audio.RecordingOptionsPresets.HIGH_QUALITY);
+  setRecording(recording);
+}
+
+async function stopRecording() {
+  await recording?.stopAndUnloadAsync();
+  const uri = recording?.getURI();
+}
+```
+
+### After (expo-audio)
+
+```tsx
+const recorder = useAudioRecorder(RecordingPresets.HIGH_QUALITY);
+
+async function startRecording() {
+  await AudioModule.requestRecordingPermissionsAsync();
+  await recorder.prepareToRecordAsync();
+  recorder.record();
+}
+
+async function stopRecording() {
+  await recorder.stop();
+  const uri = recorder.uri;
+}
+```
+
+## Audio Mode
+
+### Before (expo-av)
+
+```tsx
+await Audio.setAudioModeAsync({
+  allowsRecordingIOS: true,
+  playsInSilentModeIOS: true,
+  staysActiveInBackground: true,
+  interruptionModeIOS: InterruptionModeIOS.DoNotMix,
+});
+```
+
+### After (expo-audio)
+
+```tsx
+await setAudioModeAsync({
+  playsInSilentMode: true,
+  shouldPlayInBackground: true,
+  interruptionMode: 'doNotMix',
+});
+```
+
+## API Mapping
+
+| expo-av | expo-audio |
+|---------|------------|
+| `Audio.Sound.createAsync()` | `useAudioPlayer(source)` |
+| `sound.playAsync()` | `player.play()` |
+| `sound.pauseAsync()` | `player.pause()` |
+| `sound.setPositionAsync(ms)` | `player.seekTo(seconds)` |
+| `sound.setVolumeAsync(vol)` | `player.volume = vol` |
+| `sound.setRateAsync(rate)` | `player.playbackRate = rate` |
+| `sound.setIsLoopingAsync(loop)` | `player.loop = loop` |
+| `sound.unloadAsync()` | Automatic via hook |
+| `playbackStatus.positionMillis` | `player.currentTime` (seconds) |
+| `playbackStatus.durationMillis` | `player.duration` (seconds) |
+| `playbackStatus.isPlaying` | `player.playing` |
+| `Audio.Recording.createAsync()` | `useAudioRecorder(preset)` |
+| `Audio.RecordingOptionsPresets.*` | `RecordingPresets.*` |
+| `recording.stopAndUnloadAsync()` | `recorder.stop()` |
+| `recording.getURI()` | `recorder.uri` |
+| `Audio.requestPermissionsAsync()` | `AudioModule.requestRecordingPermissionsAsync()` |
+
+## Key Differences
+
+- **No auto-reset on finish**: After `play()` completes, the player stays paused at the end. To replay, call `player.seekTo(0)` then `play()`
+- **Time in seconds**: expo-audio uses seconds, not milliseconds (matching web standards)
+- **Immediate loading**: Audio loads immediately when the hook mounts—no explicit preloading needed
+- **Automatic cleanup**: No need to call `unloadAsync()`, hooks handle resource cleanup on unmount
+- **Multiple players**: Create multiple `useAudioPlayer` instances and store them—all load immediately
+- **Direct property access**: Set volume, rate, loop directly on the player object (`player.volume = 0.5`)
+
+## API Reference
+
+https://docs.expo.dev/versions/latest/sdk/audio/