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/building-native-ui/references/route-structure.md

@@ -0,0 +1,229 @@
+# Route Structure
+
+## File Conventions
+
+- Routes belong in the `app` directory
+- Use `[]` for dynamic routes, e.g. `[id].tsx`
+- Routes can never be named `(foo).tsx` - use `(foo)/index.tsx` instead
+- Use `(group)` routes to simplify the public URL structure
+- NEVER co-locate components, types, or utilities in the app directory - these should be in separate directories like `components/`, `utils/`, etc.
+- The app directory should only contain route and `_layout` files; every file should export a default component
+- Ensure the app always has a route that matches "/" so the app is never blank
+- ALWAYS use `_layout.tsx` files to define stacks
+
+## Dynamic Routes
+
+Use square brackets for dynamic segments:
+
+```
+app/
+  users/
+    [id].tsx        # Matches /users/123, /users/abc
+    [id]/
+      posts.tsx     # Matches /users/123/posts
+```
+
+### Catch-All Routes
+
+Use `[...slug]` for catch-all routes:
+
+```
+app/
+  docs/
+    [...slug].tsx   # Matches /docs/a, /docs/a/b, /docs/a/b/c
+```
+
+## Query Parameters
+
+Access query parameters with the `useLocalSearchParams` hook:
+
+```tsx
+import { useLocalSearchParams } from "expo-router";
+
+function Page() {
+  const { id } = useLocalSearchParams<{ id: string }>();
+}
+```
+
+For dynamic routes, the parameter name matches the file name:
+
+- `[id].tsx` → `useLocalSearchParams<{ id: string }>()`
+- `[slug].tsx` → `useLocalSearchParams<{ slug: string }>()`
+
+## Pathname
+
+Access the current pathname with the `usePathname` hook:
+
+```tsx
+import { usePathname } from "expo-router";
+
+function Component() {
+  const pathname = usePathname(); // e.g. "/users/123"
+}
+```
+
+## Group Routes
+
+Use parentheses for groups that don't affect the URL:
+
+```
+app/
+  (auth)/
+    login.tsx       # URL: /login
+    register.tsx    # URL: /register
+  (main)/
+    index.tsx       # URL: /
+    settings.tsx    # URL: /settings
+```
+
+Groups are useful for:
+
+- Organizing related routes
+- Applying different layouts to route groups
+- Keeping URLs clean
+
+## Stacks and Tabs Structure
+
+When an app has tabs, the header and title should be set in a Stack that is nested INSIDE each tab. This allows tabs to have their own headers and distinct histories. The root layout should often not have a header.
+
+- Set the 'headerShown' option to false on the tab layout
+- Use (group) routes to simplify the public URL structure
+- You may need to delete or refactor existing routes to fit this structure
+
+Example structure:
+
+```
+app/
+  _layout.tsx — <Tabs />
+  (home)/
+    _layout.tsx — <Stack />
+    index.tsx — <ScrollView />
+  (settings)/
+    _layout.tsx — <Stack />
+    index.tsx — <ScrollView />
+  (home,settings)/
+    info.tsx — <ScrollView /> (shared across tabs)
+```
+
+## Array Routes for Multiple Stacks
+
+Use array routes '(index,settings)' to create multiple stacks. This is useful for tabs that need to share screens across stacks.
+
+```
+app/
+  _layout.tsx — <Tabs />
+  (index,settings)/
+    _layout.tsx — <Stack />
+    index.tsx — <ScrollView />
+    settings.tsx — <ScrollView />
+```
+
+This requires a specialized layout with explicit anchor routes:
+
+```tsx
+// app/(index,settings)/_layout.tsx
+import { useMemo } from "react";
+import Stack from "expo-router/stack";
+
+export const unstable_settings = {
+  index: { anchor: "index" },
+  settings: { anchor: "settings" },
+};
+
+export default function Layout({ segment }: { segment: string }) {
+  const screen = segment.match(/\((.*)\)/)?.[1]!;
+
+  const options = useMemo(() => {
+    switch (screen) {
+      case "index":
+        return { headerRight: () => <></> };
+      default:
+        return {};
+    }
+  }, [screen]);
+
+  return (
+    <Stack>
+      <Stack.Screen name={screen} options={options} />
+    </Stack>
+  );
+}
+```
+
+## Complete App Structure Example
+
+```
+app/
+  _layout.tsx — <NativeTabs />
+  (index,search)/
+    _layout.tsx — <Stack />
+    index.tsx — Main list
+    search.tsx — Search view
+    i/[id].tsx — Detail page
+components/
+  theme.tsx
+  list.tsx
+utils/
+  storage.ts
+  use-search.ts
+```
+
+## Layout Files
+
+Every directory can have a `_layout.tsx` file that wraps all routes in that directory:
+
+```tsx
+// app/_layout.tsx
+import { Stack } from "expo-router/stack";
+
+export default function RootLayout() {
+  return <Stack />;
+}
+```
+
+```tsx
+// app/(tabs)/_layout.tsx
+import { NativeTabs, Icon, Label } from "expo-router/unstable-native-tabs";
+
+export default function TabLayout() {
+  return (
+    <NativeTabs>
+      <NativeTabs.Trigger name="index">
+        <Label>Home</Label>
+        <Icon sf="house.fill" />
+      </NativeTabs.Trigger>
+    </NativeTabs>
+  );
+}
+```
+
+## Route Settings
+
+Export `unstable_settings` to configure route behavior:
+
+```tsx
+export const unstable_settings = {
+  anchor: "index",
+};
+```
+
+- `initialRouteName` was renamed to `anchor` in v4
+
+## Not Found Routes
+
+Create a `+not-found.tsx` file to handle unmatched routes:
+
+```tsx
+// app/+not-found.tsx
+import { Link } from "expo-router";
+import { View, Text } from "react-native";
+
+export default function NotFound() {
+  return (
+    <View>
+      <Text>Page not found</Text>
+      <Link href="/">Go home</Link>
+    </View>
+  );
+}
+```