fix(sms): stop sending platform to the relay gateway

With platform "kave" (Kavenegar) the gateway answered "cURL library is not
loaded" and nothing was delivered. The body is now { phone, host, text } and
the gateway picks the line itself. SMS_RELAY_PLATFORM is removed from the
driver, docker-compose and the env examples.

Tests: sms.service.spec updated. 150 tests pass.

پیامک بدون انتخاب خط کاوه‌نگار فرستاده می‌شود و سرویس پیامک خودش خط را انتخاب می‌کند.

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

docker-compose.yml

@@ -56,7 +56,6 @@ services:
       - SMS_RELAY_URL=${SMS_RELAY_URL:-}
       - SMS_RELAY_SECRET=${SMS_RELAY_SECRET:-}
       - SMS_RELAY_HOST=${SMS_RELAY_HOST:-}
-      - SMS_RELAY_PLATFORM=${SMS_RELAY_PLATFORM:-}
       - SMS_TREZ_URL=${SMS_TREZ_URL:-}
       - SMS_TREZ_USERNAME=${SMS_TREZ_USERNAME:-}
       - SMS_TREZ_PASSWORD=${SMS_TREZ_PASSWORD:-}