Send verification SMS on the service line so carriers deliver the code.

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

src/sms/sms.types.ts

@@ -1,6 +1,8 @@
 export type SendSmsInput = {
   to: string;
   message: string;
+  /** Gama shortcode. OTP must use the service line; the partner default is advertising. */
+  source?: string;
 };
 
 export type SendSmsResult = {