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/storage.md

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+# Storage
+
+## Key-Value Storage
+
+Use the localStorage polyfill for key-value storage. **Never use AsyncStorage**
+
+```tsx
+import "expo-sqlite/localStorage/install";
+
+// Simple get/set
+localStorage.setItem("key", "value");
+localStorage.getItem("key");
+
+// Store objects as JSON
+localStorage.setItem("user", JSON.stringify({ name: "John", id: 1 }));
+const user = JSON.parse(localStorage.getItem("user") ?? "{}");
+```
+
+## When to Use What
+
+| Use Case                                             | Solution                |
+| ---------------------------------------------------- | ----------------------- |
+| Simple key-value (settings, preferences, small data) | `localStorage` polyfill |
+| Large datasets, complex queries, relational data     | Full `expo-sqlite`      |
+| Sensitive data (tokens, passwords)                   | `expo-secure-store`     |
+
+## Storage with React State
+
+Create a storage utility with subscriptions for reactive updates:
+
+```tsx
+// utils/storage.ts
+import "expo-sqlite/localStorage/install";
+
+type Listener = () => void;
+const listeners = new Map<string, Set<Listener>>();
+
+export const storage = {
+  get<T>(key: string, defaultValue: T): T {
+    const value = localStorage.getItem(key);
+    return value ? JSON.parse(value) : defaultValue;
+  },
+
+  set<T>(key: string, value: T): void {
+    localStorage.setItem(key, JSON.stringify(value));
+    listeners.get(key)?.forEach((fn) => fn());
+  },
+
+  subscribe(key: string, listener: Listener): () => void {
+    if (!listeners.has(key)) listeners.set(key, new Set());
+    listeners.get(key)!.add(listener);
+    return () => listeners.get(key)?.delete(listener);
+  },
+};
+```
+
+## React Hook for Storage
+
+```tsx
+// hooks/use-storage.ts
+import { useSyncExternalStore } from "react";
+import { storage } from "@/utils/storage";
+
+export function useStorage<T>(
+  key: string,
+  defaultValue: T
+): [T, (value: T) => void] {
+  const value = useSyncExternalStore(
+    (cb) => storage.subscribe(key, cb),
+    () => storage.get(key, defaultValue)
+  );
+
+  return [value, (newValue: T) => storage.set(key, newValue)];
+}
+```
+
+Usage:
+
+```tsx
+function Settings() {
+  const [theme, setTheme] = useStorage("theme", "light");
+
+  return (
+    <Switch
+      value={theme === "dark"}
+      onValueChange={(dark) => setTheme(dark ? "dark" : "light")}
+    />
+  );
+}
+```
+
+## Full SQLite for Complex Data
+
+For larger datasets or complex queries, use expo-sqlite directly:
+
+```tsx
+import * as SQLite from "expo-sqlite";
+
+const db = await SQLite.openDatabaseAsync("app.db");
+
+// Create table
+await db.execAsync(`
+  CREATE TABLE IF NOT EXISTS events (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    title TEXT NOT NULL,
+    date TEXT NOT NULL,
+    location TEXT
+  )
+`);
+
+// Insert
+await db.runAsync("INSERT INTO events (title, date) VALUES (?, ?)", [
+  "Meeting",
+  "2024-01-15",
+]);
+
+// Query
+const events = await db.getAllAsync("SELECT * FROM events WHERE date > ?", [
+  "2024-01-01",
+]);
+```