Add mobile module to Base44 SDK for push notifications

Implements mobile native capabilities in the SDK, allowing apps to send
push notifications to users. This exposes the backend mobile API to
LLM-generated apps through base44.mobile.sendNotification().

SDK changes:
- Create mobile module with sendNotification() method
- Add TypeScript types for mobile notifications
- Add mobile module to Base44Client interface
- Export mobile types from index.ts
- Update README with mobile features documentation
- Add comprehensive mobile notifications examples

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: gdauber1

README.md

@@ -13,6 +13,7 @@ The SDK provides access to Base44's functionality through the following modules:
 - **[`entities`](https://docs.base44.com/sdk-docs/interfaces/entities)**: Work with your app's data entities using CRUD operations.
 - **[`functions`](https://docs.base44.com/sdk-docs/interfaces/functions)**: Execute backend functions.
 - **[`integrations`](https://docs.base44.com/sdk-docs/type-aliases/integrations)**: Pre-built server-side functions for external services.
+- **[`mobile`](#mobile-native-features)**: Send push notifications and access mobile native capabilities.
 
 ## Example
 
@@ -37,6 +38,135 @@ await base44.entities.Task.update(newTask.id, {
 const tasks = await base44.entities.Task.list();
 ```
 
+## Mobile Native Features
+
+The SDK provides mobile native capabilities through the `mobile` module, allowing you to send push notifications to your app users.
+
+### Push Notifications
+
+Send push notifications to users on mobile devices:
+
+```typescript
+import { base44 } from "@/api/base44Client";
+
+// Send a push notification to a user
+await base44.mobile.sendNotification({
+  userId: "user_123",
+  title: "New Message!",
+  content: "You have a new message from John",
+  actionLabel: "View Message",
+  actionUrl: "/messages/456",
+  channels: ["mobile_push"], // Mobile push only
+});
+
+// Send to both mobile push and in-app notifications (default)
+await base44.mobile.sendNotification({
+  userId: "user_456",
+  title: "Order Shipped",
+  content: "Your order #12345 has been shipped and is on its way!",
+  actionLabel: "Track Order",
+  actionUrl: "/orders/12345",
+});
+```
+
+### Notification Channels
+
+The `mobile` module supports two notification channels:
+
+- **`mobile_push`**: Sends a push notification to the user's mobile device (iOS/Android)
+- **`in_app`**: Sends an in-app notification visible in the web interface
+
+By default, notifications are sent to both channels. You can specify specific channels using the `channels` parameter:
+
+```typescript
+// Mobile push only - user will receive push notification on their phone
+await base44.mobile.sendNotification({
+  userId: "user_123",
+  title: "Time-sensitive alert",
+  content: "Your session will expire in 5 minutes",
+  channels: ["mobile_push"],
+});
+
+// In-app only - notification visible only in the web interface
+await base44.mobile.sendNotification({
+  userId: "user_789",
+  title: "System Update",
+  content: "We've updated the dashboard with new features",
+  channels: ["in_app"],
+});
+```
+
+### Common Use Cases
+
+**Order & Delivery Updates**:
+```typescript
+// Notify user when order is ready
+await base44.mobile.sendNotification({
+  userId: order.userId,
+  title: "Order Ready for Pickup",
+  content: `Your order #${order.id} is ready at ${store.name}`,
+  actionLabel: "View Order",
+  actionUrl: `/orders/${order.id}`,
+});
+```
+
+**Chat & Messaging**:
+```typescript
+// Notify user of new messages
+await base44.mobile.sendNotification({
+  userId: recipient.id,
+  title: `New message from ${sender.name}`,
+  content: message.preview,
+  actionLabel: "Reply",
+  actionUrl: `/chats/${conversation.id}`,
+  channels: ["mobile_push"], // Mobile only, avoid duplicate with in-app chat
+});
+```
+
+**Reminders & Events**:
+```typescript
+// Send event reminder
+await base44.mobile.sendNotification({
+  userId: attendee.userId,
+  title: "Event Starting Soon",
+  content: `${event.name} starts in 30 minutes`,
+  actionLabel: "View Details",
+  actionUrl: `/events/${event.id}`,
+});
+```
+
+### Error Handling
+
+The notification API handles errors gracefully:
+
+```typescript
+try {
+  const result = await base44.mobile.sendNotification({
+    userId: "user_123",
+    title: "Test Notification",
+    content: "This is a test",
+  });
+
+  if (result.success) {
+    console.log("Notification sent successfully");
+    console.log("Notification ID:", result.notificationId);
+  }
+} catch (error) {
+  if (error.status === 404) {
+    console.error("User not found");
+  } else if (error.status === 403) {
+    console.error("Not authorized to send notifications");
+  } else {
+    console.error("Failed to send notification:", error.message);
+  }
+}
+```
+
+**Graceful Degradation**:
+- If a user doesn't have mobile push enabled, the notification is still sent to other channels
+- If one channel fails, other channels still receive the notification
+- Notifications are queued and retried automatically for temporary failures
+
 ## Learn more
 
 For complete documentation, guides, and API reference, visit the **[Base44 SDK Documentation](https://docs.base44.com/sdk-getting-started/overview)**.