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/native-tabs.md

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+# Native Tabs Migration (SDK 55)
+
+In SDK 55, `Label`, `Icon`, `Badge`, and `VectorIcon` are now accessed as static properties on `NativeTabs.Trigger` rather than separate imports.
+
+## Import Changes
+
+```tsx
+// SDK 53/54
+import {
+  NativeTabs,
+  Icon,
+  Label,
+  Badge,
+  VectorIcon,
+} from "expo-router/unstable-native-tabs";
+
+// SDK 55+
+import { NativeTabs } from "expo-router/unstable-native-tabs";
+```
+
+## Component Changes
+
+| SDK 53/54        | SDK 55+                             |
+| ---------------- | ----------------------------------- |
+| `<Icon />`       | `<NativeTabs.Trigger.Icon />`       |
+| `<Label />`      | `<NativeTabs.Trigger.Label />`      |
+| `<Badge />`      | `<NativeTabs.Trigger.Badge />`      |
+| `<VectorIcon />` | `<NativeTabs.Trigger.VectorIcon />` |
+| (n/a)            | `<NativeTabs.BottomAccessory />`    |
+
+## New in SDK 55
+
+### BottomAccessory
+
+New component for Apple Music-style mini players on iOS +26 that float above the tab bar:
+
+```tsx
+<NativeTabs>
+  <NativeTabs.BottomAccessory>
+    {/* Content above tabs */}
+  </NativeTabs.BottomAccessory>
+  <NativeTabs.Trigger name="(index)">
+    <NativeTabs.Trigger.Label>Home</NativeTabs.Trigger.Label>
+  </NativeTabs.Trigger>
+</NativeTabs>
+```
+
+On Android and web, this component will render as a no-op. Position a view absolutely above the tab bar instead.
+
+### Icon `md` Prop
+
+New `md` prop for Material icon glyphs on Android (alongside existing `drawable`):
+
+```tsx
+<NativeTabs.Trigger.Icon sf="house" md="home" />
+```
+
+## Full Migration Example
+
+### Before (SDK 53/54)
+
+```tsx
+import {
+  NativeTabs,
+  Icon,
+  Label,
+  Badge,
+} from "expo-router/unstable-native-tabs";
+
+export default function TabLayout() {
+  return (
+    <NativeTabs minimizeBehavior="onScrollDown">
+      <NativeTabs.Trigger name="(index)">
+        <Label>Home</Label>
+        <Icon sf="house.fill" />
+        <Badge>3</Badge>
+      </NativeTabs.Trigger>
+      <NativeTabs.Trigger name="(settings)">
+        <Label>Settings</Label>
+        <Icon sf="gear" />
+      </NativeTabs.Trigger>
+      <NativeTabs.Trigger name="(search)" role="search">
+        <Label>Search</Label>
+      </NativeTabs.Trigger>
+    </NativeTabs>
+  );
+}
+```
+
+### After (SDK 55+)
+
+```tsx
+import { NativeTabs } from "expo-router/unstable-native-tabs";
+
+export default function TabLayout() {
+  return (
+    <NativeTabs minimizeBehavior="onScrollDown">
+      <NativeTabs.Trigger name="(index)">
+        <NativeTabs.Trigger.Label>Home</NativeTabs.Trigger.Label>
+        <NativeTabs.Trigger.Icon sf="house.fill" md="home" />
+        <NativeTabs.Trigger.Badge>3</NativeTabs.Trigger.Badge>
+      </NativeTabs.Trigger>
+      <NativeTabs.Trigger name="(settings)">
+        <NativeTabs.Trigger.Label>Settings</NativeTabs.Trigger.Label>
+        <NativeTabs.Trigger.Icon sf="gear" md="settings" />
+      </NativeTabs.Trigger>
+      <NativeTabs.Trigger name="(search)" role="search">
+        <NativeTabs.Trigger.Label>Search</NativeTabs.Trigger.Label>
+      </NativeTabs.Trigger>
+    </NativeTabs>
+  );
+}
+```
+
+## Migration Checklist
+
+1. Remove `Icon`, `Label`, `Badge`, `VectorIcon` from imports
+2. Keep only `NativeTabs` import from `expo-router/unstable-native-tabs`
+3. Replace `<Icon />` with `<NativeTabs.Trigger.Icon />`
+4. Replace `<Label />` with `<NativeTabs.Trigger.Label />`
+5. Replace `<Badge />` with `<NativeTabs.Trigger.Badge />`
+6. Replace `<VectorIcon />` with `<NativeTabs.Trigger.VectorIcon />`
+
+- Read docs for more info https://docs.expo.dev/versions/v55.0.0/sdk/router-native-tabs/