Add EXPO example to docs/postgresql

Author: Gioee

docs/postgresql/CLIENT.md

@@ -22,9 +22,8 @@ Under the hood, SQLite Sync uses advanced **CRDT (Conflict-free Replicated Data
 
 - Updated example apps are available [here](https://github.com/sqliteai/sqlite-sync-dev/tree/main/examples):  
   - sport-tracker app (WASM), see [SPORT_APP_README_SUPABASE.md](SPORT_APP_README_SUPABASE.md) for more details
-  - to-do app (Expo)
+  - to-do app (Expo), see [EXPO.md](EXPO.md) for more details
   - React Native Library: https://github.com/sqliteai/sqlite-sync-react-native
-  - Remaining demos will be updated in the next days
 
 ## Conversion Between SQLite and PostgreSQL Tables
 

docs/postgresql/EXPO.md

@@ -0,0 +1,57 @@
+# Expo CloudSync Example
+
+A simple Expo example demonstrating SQLite synchronization with CloudSync and PostgreSQL. Build cross-platform apps that sync data seamlessly across devices.
+
+<img src="https://github.com/user-attachments/assets/86db5c25-d8ff-4c31-b157-8dff178e1720" width="40%" height="40%">
+
+## 🚀 Quick Start
+
+### 1. Clone the template
+
+Create a new project using this template:
+```bash
+npx create-expo-app MyApp --template @sqliteai/todoapp@dev
+cd MyApp
+```
+
+### 2. Setup
+
+1. Execute the exact schema from `to-do-app.sql`.
+2. Rename the `.env.example` into `.env` and fill with your values.
+3. If you're testing with a local server define also the `ANDROID_CONNECTION_STRING` variable and use a different connection string for it, replace localhost with `10.0.2.2`.
+
+```
+CONNECTION_STRING="http://localhost:8091/postgres"
+ANDROID_CONNECTION_STRING="http://10.0.2.2:8091/postgres"
+API_TOKEN="token"
+```
+
+4. Fill the `API_TOKEN` variable with the token from the `CloudSync` service.
+
+> **⚠️ SECURITY WARNING**: This example puts database connection strings directly in `.env` files for demonstration purposes only. **Do not use this pattern in production.** 
+>
+> **Why this is unsafe:**
+> - Connection strings contain sensitive credentials
+> - Client-side apps expose all environment variables to users
+> - Anyone can inspect your app and extract database credentials
+>
+> **For production apps:**
+> - Use the secure [sport-tracker-app](https://github.com/sqliteai/sqlite-sync-dev/tree/main/examples/sport-tracker-app) pattern with authentication tokens and row-level security
+> - Never embed database credentials in client applications
+
+### 4. Build and run the App
+
+```bash
+npx expo prebuild # run once
+npm run ios # or android
+```
+
+## ✨ Features
+
+- **Add Tasks** - Create new tasks with titles and optional tags.
+- **Edit Task Status** - Update task status when completed.
+- **Delete Tasks** - Remove tasks from your list.
+- **Dropdown Menu** - Select categories for tasks from a predefined list.
+- **Cross-Platform** - Works on iOS and Android
+- **Offline Support** - Works offline, syncs when connection returns
+