Add optional SMS auto-block threshold below balance.

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

prisma/migrations/20260808140000_sms_auto_block_below/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE `sms_accounts` ADD COLUMN `auto_block_below_rials` INTEGER NULL;