feat: Implement notification system with 3 subpages (Events, Channels, Templates)

## ✅ Correct Implementation Following NOTIFICATION_STRATEGY.md

### Frontend (React) - 3 Subpages

**1. Main Notifications Page** (`Notifications.tsx`)
- Tab navigation for 3 sections
- Events | Channels | Templates

**2. Events Subpage** (`Notifications/Events.tsx`)
- Configure which channels per event
- Grouped by category (Orders, Products, Customers)
- Toggle channels (Email, WhatsApp, Telegram, etc.)
- Show recipient (Admin/Customer/Both)
- Switch UI for enable/disable per channel

**3. Channels Subpage** (`Notifications/Channels.tsx`)
- List available channels
- Built-in channels (Email)
- Addon channels (WhatsApp, Telegram, SMS, Push)
- Channel status (Active/Inactive)
- Configure button for each channel
- Addon discovery cards

**4. Templates Subpage** (`Notifications/Templates.tsx`)
- Email templates (link to WooCommerce)
- Addon channel templates
- Template variables reference
- Preview and edit buttons
- Variable documentation ({order_number}, {customer_name}, etc.)

### Backend (PHP) - Bridge to WooCommerce

**NotificationsController** (`includes/Api/NotificationsController.php`)
- Bridges to WooCommerce email system
- Does NOT reinvent notification system
- Provides addon integration hooks

**REST API Endpoints:**
```
GET  /notifications/channels  - List channels (email + addons)
GET  /notifications/events     - List events (maps to WC emails)
POST /notifications/events/update - Update event channel settings
```

**Key Features:**
✅ Leverages WooCommerce emails (not reinventing)
✅ Stores settings in wp_options
✅ Provides hooks for addons:
   - `woonoow_notification_channels` filter
   - `woonoow_notification_events` filter
   - `woonoow_notification_event_updated` action

### Addon Integration

**Example: WhatsApp Addon**
```php
// Register channel
add_filter("woonoow_notification_channels", function($channels) {
    $channels[] = [
        "id" => "whatsapp",
        "label" => "WhatsApp",
        "icon" => "message-circle",
        "enabled" => true,
        "addon" => "woonoow-whatsapp",
    ];
    return $channels;
});

// React to event updates
add_action("woonoow_notification_event_updated", function($event_id, $channel_id, $enabled, $recipient) {
    if ($channel_id === "whatsapp" && $enabled) {
        // Setup WhatsApp notification for this event
    }
}, 10, 4);

// Hook into WooCommerce email triggers
add_action("woocommerce_order_status_processing", function($order_id) {
    // Send WhatsApp notification
}, 10, 1);
```

### Architecture

**NOT a new notification system** ✅
- Uses WooCommerce email infrastructure
- Maps events to WC email IDs
- Addons hook into WC triggers

**IS an extensible framework** ✅
- Unified UI for all channels
- Per-event channel configuration
- Template management
- Addon discovery

### Files Created
- `Notifications.tsx` - Main page with tabs
- `Notifications/Events.tsx` - Events configuration
- `Notifications/Channels.tsx` - Channel management
- `Notifications/Templates.tsx` - Template editor
- `NotificationsController.php` - REST API bridge

### Files Modified
- `Routes.php` - Register NotificationsController

---

**Ready for addon development!** 🚀
Next: Build Telegram addon as proof of concept

includes/Api/NotificationsController.php

@@ -2,7 +2,7 @@
 /**
  * Notifications REST API Controller
  * 
- * Handles notification settings API endpoints.
+ * Bridge to WooCommerce emails + addon channel framework.
  * 
  * @package WooNooW\Api
  */
@@ -12,8 +12,6 @@ namespace WooNooW\Api;
 use WP_REST_Request;
 use WP_REST_Response;
 use WP_Error;
-use WooNooW\Core\Notifications\NotificationManager;
-use WooNooW\Core\Notifications\NotificationSettingsProvider;
 
 class NotificationsController {
 	
@@ -49,20 +47,11 @@ class NotificationsController {
 			],
 		]);
 		
-		// GET /woonoow/v1/notifications/settings
-		register_rest_route($this->namespace, '/' . $this->rest_base . '/settings', [
-			[
-				'methods' => 'GET',
-				'callback' => [$this, 'get_settings'],
-				'permission_callback' => [$this, 'check_permission'],
-			],
-		]);
-		
-		// POST /woonoow/v1/notifications/settings
-		register_rest_route($this->namespace, '/' . $this->rest_base . '/settings', [
+		// POST /woonoow/v1/notifications/events/update
+		register_rest_route($this->namespace, '/' . $this->rest_base . '/events/update', [
 			[
 				'methods' => 'POST',
-				'callback' => [$this, 'update_settings'],
+				'callback' => [$this, 'update_event'],
 				'permission_callback' => [$this, 'check_permission'],
 			],
 		]);
@@ -75,17 +64,20 @@ class NotificationsController {
 	 * @return WP_REST_Response
 	 */
 	public function get_channels(WP_REST_Request $request) {
-		$channels = NotificationManager::get_channels();
+		$channels = [
+			[
+				'id' => 'email',
+				'label' => __('Email', 'woonoow'),
+				'icon' => 'mail',
+				'enabled' => true,
+				'builtin' => true,
+			],
+		];
 		
-		// Add enabled status from settings
-		$settings = NotificationSettingsProvider::get_settings();
-		$channel_settings = $settings['channels'] ?? [];
+		// Allow addons to register their channels
+		$channels = apply_filters('woonoow_notification_channels', $channels);
 		
-		foreach ($channels as $id => &$channel) {
-			$channel['enabled'] = $channel_settings[$id]['enabled'] ?? $channel['builtin'];
-		}
-		
-		return new WP_REST_Response(array_values($channels), 200);
+		return new WP_REST_Response($channels, 200);
 	}
 	
 	/**
@@ -95,78 +87,148 @@ class NotificationsController {
 	 * @return WP_REST_Response
 	 */
 	public function get_events(WP_REST_Request $request) {
-		$events = NotificationManager::get_events();
-		$settings = NotificationSettingsProvider::get_settings();
-		$event_settings = $settings['events'] ?? [];
+		// Get saved settings
+		$settings = get_option('woonoow_notification_settings', []);
 		
-		// Merge event data with settings
-		foreach ($events as $id => &$event) {
-			$event_config = $event_settings[$id] ?? [];
-			$event['enabled'] = $event_config['enabled'] ?? true;
-			$event['channels'] = $event_config['channels'] ?? ['email'];
-			$event['recipients'] = $event_config['recipients'] ?? ['email' => 'admin'];
-		}
-		
-		// Group by category
-		$grouped = [
-			'orders' => [],
-			'products' => [],
-			'customers' => [],
+		// Define default events (maps to WooCommerce emails)
+		$events = [
+			'orders' => [
+				[
+					'id' => 'order_placed',
+					'label' => __('Order Placed', 'woonoow'),
+					'description' => __('When a new order is placed', 'woonoow'),
+					'category' => 'orders',
+					'wc_email' => 'new_order',
+					'enabled' => true,
+					'channels' => $settings['order_placed'] ?? ['email' => ['enabled' => true, 'recipient' => 'admin']],
+				],
+				[
+					'id' => 'order_processing',
+					'label' => __('Order Processing', 'woonoow'),
+					'description' => __('When order status changes to processing', 'woonoow'),
+					'category' => 'orders',
+					'wc_email' => 'customer_processing_order',
+					'enabled' => true,
+					'channels' => $settings['order_processing'] ?? ['email' => ['enabled' => true, 'recipient' => 'customer']],
+				],
+				[
+					'id' => 'order_completed',
+					'label' => __('Order Completed', 'woonoow'),
+					'description' => __('When order is marked as completed', 'woonoow'),
+					'category' => 'orders',
+					'wc_email' => 'customer_completed_order',
+					'enabled' => true,
+					'channels' => $settings['order_completed'] ?? ['email' => ['enabled' => true, 'recipient' => 'customer']],
+				],
+				[
+					'id' => 'order_cancelled',
+					'label' => __('Order Cancelled', 'woonoow'),
+					'description' => __('When order is cancelled', 'woonoow'),
+					'category' => 'orders',
+					'wc_email' => 'cancelled_order',
+					'enabled' => true,
+					'channels' => $settings['order_cancelled'] ?? ['email' => ['enabled' => true, 'recipient' => 'admin']],
+				],
+				[
+					'id' => 'order_refunded',
+					'label' => __('Order Refunded', 'woonoow'),
+					'description' => __('When order is refunded', 'woonoow'),
+					'category' => 'orders',
+					'wc_email' => 'customer_refunded_order',
+					'enabled' => true,
+					'channels' => $settings['order_refunded'] ?? ['email' => ['enabled' => true, 'recipient' => 'customer']],
+				],
+			],
+			'products' => [
+				[
+					'id' => 'low_stock',
+					'label' => __('Low Stock Alert', 'woonoow'),
+					'description' => __('When product stock is low', 'woonoow'),
+					'category' => 'products',
+					'wc_email' => 'low_stock',
+					'enabled' => true,
+					'channels' => $settings['low_stock'] ?? ['email' => ['enabled' => true, 'recipient' => 'admin']],
+				],
+				[
+					'id' => 'out_of_stock',
+					'label' => __('Out of Stock Alert', 'woonoow'),
+					'description' => __('When product is out of stock', 'woonoow'),
+					'category' => 'products',
+					'wc_email' => 'no_stock',
+					'enabled' => true,
+					'channels' => $settings['out_of_stock'] ?? ['email' => ['enabled' => true, 'recipient' => 'admin']],
+				],
+			],
+			'customers' => [
+				[
+					'id' => 'new_customer',
+					'label' => __('New Customer', 'woonoow'),
+					'description' => __('When a new customer registers', 'woonoow'),
+					'category' => 'customers',
+					'wc_email' => 'customer_new_account',
+					'enabled' => true,
+					'channels' => $settings['new_customer'] ?? ['email' => ['enabled' => true, 'recipient' => 'customer']],
+				],
+				[
+					'id' => 'customer_note',
+					'label' => __('Customer Note Added', 'woonoow'),
+					'description' => __('When a note is added to customer order', 'woonoow'),
+					'category' => 'customers',
+					'wc_email' => 'customer_note',
+					'enabled' => true,
+					'channels' => $settings['customer_note'] ?? ['email' => ['enabled' => true, 'recipient' => 'customer']],
+				],
+			],
 		];
 		
-		foreach ($events as $event) {
-			$category = $event['category'] ?? 'general';
-			if (!isset($grouped[$category])) {
-				$grouped[$category] = [];
-			}
-			$grouped[$category][] = $event;
-		}
+		// Allow addons to add custom events
+		$events = apply_filters('woonoow_notification_events', $events);
 		
-		return new WP_REST_Response($grouped, 200);
+		return new WP_REST_Response($events, 200);
 	}
 	
 	/**
-	 * Get notification settings
-	 * 
-	 * @param WP_REST_Request $request Request object
-	 * @return WP_REST_Response
-	 */
-	public function get_settings(WP_REST_Request $request) {
-		$settings = NotificationSettingsProvider::get_settings();
-		return new WP_REST_Response($settings, 200);
-	}
-	
-	/**
-	 * Update notification settings
+	 * Update event settings
 	 * 
 	 * @param WP_REST_Request $request Request object
 	 * @return WP_REST_Response|WP_Error
 	 */
-	public function update_settings(WP_REST_Request $request) {
-		$new_settings = $request->get_json_params();
+	public function update_event(WP_REST_Request $request) {
+		$event_id = $request->get_param('eventId');
+		$channel_id = $request->get_param('channelId');
+		$enabled = $request->get_param('enabled');
+		$recipient = $request->get_param('recipient');
 		
-		if (empty($new_settings)) {
+		if (empty($event_id) || empty($channel_id)) {
 			return new WP_Error(
-				'invalid_settings',
-				__('Invalid settings data', 'woonoow'),
+				'invalid_params',
+				__('Event ID and Channel ID are required', 'woonoow'),
 				['status' => 400]
 			);
 		}
 		
-		$updated = NotificationSettingsProvider::update_settings($new_settings);
+		// Get current settings
+		$settings = get_option('woonoow_notification_settings', []);
 		
-		if (!$updated) {
-			return new WP_Error(
-				'update_failed',
-				__('Failed to update notification settings', 'woonoow'),
-				['status' => 500]
-			);
+		// Update settings
+		if (!isset($settings[$event_id])) {
+			$settings[$event_id] = [];
 		}
 		
+		$settings[$event_id][$channel_id] = [
+			'enabled' => $enabled,
+			'recipient' => $recipient ?? 'admin',
+		];
+		
+		// Save settings
+		update_option('woonoow_notification_settings', $settings);
+		
+		// Fire action for addons to react
+		do_action('woonoow_notification_event_updated', $event_id, $channel_id, $enabled, $recipient);
+		
 		return new WP_REST_Response([
 			'success' => true,
-			'message' => __('Notification settings updated successfully', 'woonoow'),
-			'settings' => NotificationSettingsProvider::get_settings(),
+			'message' => __('Event settings updated successfully', 'woonoow'),
 		], 200);
 	}