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/search.md

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+# Search
+
+## Header Search Bar
+
+Add a search bar to the stack header with `headerSearchBarOptions`:
+
+```tsx
+<Stack.Screen
+  name="index"
+  options={{
+    headerSearchBarOptions: {
+      placeholder: "Search",
+      onChangeText: (event) => console.log(event.nativeEvent.text),
+    },
+  }}
+/>
+```
+
+### Options
+
+```tsx
+headerSearchBarOptions: {
+  // Placeholder text
+  placeholder: "Search items...",
+
+  // Auto-capitalize behavior
+  autoCapitalize: "none",
+
+  // Input type
+  inputType: "text", // "text" | "phone" | "number" | "email"
+
+  // Cancel button text (iOS)
+  cancelButtonText: "Cancel",
+
+  // Hide when scrolling (iOS)
+  hideWhenScrolling: true,
+
+  // Hide navigation bar during search (iOS)
+  hideNavigationBar: true,
+
+  // Obscure background during search (iOS)
+  obscureBackground: true,
+
+  // Placement
+  placement: "automatic", // "automatic" | "inline" | "stacked"
+
+  // Callbacks
+  onChangeText: (event) => {},
+  onSearchButtonPress: (event) => {},
+  onCancelButtonPress: (event) => {},
+  onFocus: () => {},
+  onBlur: () => {},
+}
+```
+
+## useSearch Hook
+
+Reusable hook for search state management:
+
+```tsx
+import { useEffect, useState } from "react";
+import { useNavigation } from "expo-router";
+
+export function useSearch(options: any = {}) {
+  const [search, setSearch] = useState("");
+  const navigation = useNavigation();
+
+  useEffect(() => {
+    navigation.setOptions({
+      headerShown: true,
+      headerSearchBarOptions: {
+        ...options,
+        onChangeText(e: any) {
+          setSearch(e.nativeEvent.text);
+          options.onChangeText?.(e);
+        },
+        onSearchButtonPress(e: any) {
+          setSearch(e.nativeEvent.text);
+          options.onSearchButtonPress?.(e);
+        },
+        onCancelButtonPress(e: any) {
+          setSearch("");
+          options.onCancelButtonPress?.(e);
+        },
+      },
+    });
+  }, [options, navigation]);
+
+  return search;
+}
+```
+
+### Usage
+
+```tsx
+function SearchScreen() {
+  const search = useSearch({ placeholder: "Search items..." });
+
+  const filteredItems = items.filter(item =>
+    item.name.toLowerCase().includes(search.toLowerCase())
+  );
+
+  return (
+    <FlatList
+      data={filteredItems}
+      renderItem={({ item }) => <ItemRow item={item} />}
+    />
+  );
+}
+```
+
+## Filtering Patterns
+
+### Simple Text Filter
+
+```tsx
+const filtered = items.filter(item =>
+  item.name.toLowerCase().includes(search.toLowerCase())
+);
+```
+
+### Multiple Fields
+
+```tsx
+const filtered = items.filter(item => {
+  const query = search.toLowerCase();
+  return (
+    item.name.toLowerCase().includes(query) ||
+    item.description.toLowerCase().includes(query) ||
+    item.tags.some(tag => tag.toLowerCase().includes(query))
+  );
+});
+```
+
+### Debounced Search
+
+For expensive filtering or API calls:
+
+```tsx
+import { useState, useEffect, useMemo } from "react";
+
+function useDebounce<T>(value: T, delay: number): T {
+  const [debounced, setDebounced] = useState(value);
+
+  useEffect(() => {
+    const timer = setTimeout(() => setDebounced(value), delay);
+    return () => clearTimeout(timer);
+  }, [value, delay]);
+
+  return debounced;
+}
+
+function SearchScreen() {
+  const search = useSearch();
+  const debouncedSearch = useDebounce(search, 300);
+
+  const filteredItems = useMemo(() =>
+    items.filter(item =>
+      item.name.toLowerCase().includes(debouncedSearch.toLowerCase())
+    ),
+    [debouncedSearch]
+  );
+
+  return <FlatList data={filteredItems} />;
+}
+```
+
+## Search with Native Tabs
+
+When using NativeTabs with a search role, the search bar integrates with the tab bar:
+
+```tsx
+// app/_layout.tsx
+<NativeTabs>
+  <NativeTabs.Trigger name="(home)">
+    <Label>Home</Label>
+    <Icon sf="house.fill" />
+  </NativeTabs.Trigger>
+  <NativeTabs.Trigger name="(search)" role="search">
+    <Label>Search</Label>
+  </NativeTabs.Trigger>
+</NativeTabs>
+```
+
+```tsx
+// app/(search)/_layout.tsx
+<Stack>
+  <Stack.Screen
+    name="index"
+    options={{
+      headerSearchBarOptions: {
+        placeholder: "Search...",
+        onChangeText: (e) => setSearch(e.nativeEvent.text),
+      },
+    }}
+  />
+</Stack>
+```
+
+## Empty States
+
+Show appropriate UI when search returns no results:
+
+```tsx
+function SearchResults({ search, items }) {
+  const filtered = items.filter(/* ... */);
+
+  if (search && filtered.length === 0) {
+    return (
+      <View style={{ flex: 1, justifyContent: "center", alignItems: "center" }}>
+        <Text style={{ color: PlatformColor("secondaryLabel") }}>
+          No results for "{search}"
+        </Text>
+      </View>
+    );
+  }
+
+  return <FlatList data={filtered} />;
+}
+```
+
+## Search Suggestions
+
+Show recent searches or suggestions:
+
+```tsx
+function SearchScreen() {
+  const search = useSearch();
+  const [recentSearches, setRecentSearches] = useState<string[]>([]);
+
+  if (!search && recentSearches.length > 0) {
+    return (
+      <View>
+        <Text style={{ color: PlatformColor("secondaryLabel") }}>
+          Recent Searches
+        </Text>
+        {recentSearches.map((term) => (
+          <Pressable key={term} onPress={() => /* apply search */}>
+            <Text>{term}</Text>
+          </Pressable>
+        ))}
+      </View>
+    );
+  }
+
+  return <SearchResults search={search} />;
+}
+```