Add per-customer SMS and Bird Integrations for event messaging.

Attendee and speaker comms use encrypted tenant relay credentials and skip platform-key fallback and Bird wallet double-debit.

Co-authored-by: Cursor <cursoragent@cursor.com>

config/sms.php

@@ -3,5 +3,6 @@
 return [
     'platform_api_url' => env('SMS_PLATFORM_API_URL', 'https://ladill.com/api'),
     'platform_api_key' => env('SMS_API_KEY_EVENTS'),
+    'customer_relay_url' => env('SMS_CUSTOMER_RELAY_URL', 'https://ladill.com/api/sms'),
     'default_sender_id' => env('SMS_DEFAULT_SENDER_ID', 'Ladill'),
 ];