Add FCM push notifications, queue alerts, caller ID fixes, and auto-revert agent status

Server-side:
- Add push credential auto-creation for FCM incoming call notifications
- Add queue alert FCM notifications (data-only for background delivery)
- Add queue alert cancellation on call accept/disconnect
- Fix caller ID to show caller's number instead of Twilio number
- Fix FCM token storage when refresh_token is null
- Add pre_call_status tracking to revert agent status 30s after call ends
- Add SSE fallback polling for mobile app connectivity

Mobile app:
- Add Android telecom permissions and phone account registration
- Add VoiceFirebaseMessagingService for incoming call push handling
- Add insistent queue alert notifications with custom sound
- Fix caller number display on active call screen
- Add caller ID selection dropdown on dashboard
- Add phone numbers endpoint and provider support
- Add unit tests for CallInfo, QueueState, and CallProvider
- Remove local.properties from tracking, add .gitignore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

includes/class-twp-fcm.php

@@ -279,22 +279,68 @@ class TWP_FCM {
     }
 
     /**
-     * Send incoming call notification
+     * Send queue alert notification (call entered queue).
+     * Uses data-only message so it works in background/killed state.
      */
-    public function notify_incoming_call($user_id, $from_number, $queue_name, $call_sid) {
-        $title = 'Incoming Call';
-        $body = "Call from $from_number in $queue_name queue";
+    public function notify_queue_alert($user_id, $from_number, $queue_name, $call_sid) {
+        $title = 'Call Waiting';
+        $body = "Call from $from_number in $queue_name";
 
         $data = array(
-            'type' => 'incoming_call',
+            'type' => 'queue_alert',
             'call_sid' => $call_sid,
             'from_number' => $from_number,
-            'queue_name' => $queue_name
+            'queue_name' => $queue_name,
         );
 
         return $this->send_notification($user_id, $title, $body, $data, true);
     }
 
+    /**
+     * Cancel queue alert notification (call answered or caller disconnected).
+     */
+    public function notify_queue_alert_cancel($user_id, $call_sid) {
+        $data = array(
+            'type' => 'queue_alert_cancel',
+            'call_sid' => $call_sid,
+        );
+
+        return $this->send_notification($user_id, '', '', $data, true);
+    }
+
+    /**
+     * Send queue alert cancel to all agents assigned to a queue.
+     */
+    public function cancel_queue_alert_for_queue($queue_id, $call_sid) {
+        global $wpdb;
+        $queue_table = $wpdb->prefix . 'twp_call_queues';
+
+        $queue = $wpdb->get_row($wpdb->prepare(
+            "SELECT * FROM $queue_table WHERE id = %d", $queue_id
+        ));
+        if (!$queue) return;
+
+        $notified_users = array();
+
+        // Notify personal queue owner
+        if (!empty($queue->user_id)) {
+            $this->notify_queue_alert_cancel($queue->user_id, $call_sid);
+            $notified_users[] = $queue->user_id;
+        }
+
+        // Notify agent group members
+        if (!empty($queue->agent_group_id)) {
+            require_once dirname(__FILE__) . '/class-twp-agent-groups.php';
+            $members = TWP_Agent_Groups::get_group_members($queue->agent_group_id);
+            foreach ($members as $member) {
+                if (!in_array($member->user_id, $notified_users)) {
+                    $this->notify_queue_alert_cancel($member->user_id, $call_sid);
+                    $notified_users[] = $member->user_id;
+                }
+            }
+        }
+    }
+
     /**
      * Send queue timeout notification
      */