perf(cmpp): decouple supplier result callbacks

api/prisma/migrations/20260820130000_add_submit_result_idempotency/migration.sql

@@ -0,0 +1,6 @@
+ALTER TABLE "SmsSubmitRecord"
+ADD COLUMN "resultEventId" TEXT,
+ADD COLUMN "resultProcessedAt" TIMESTAMP(3);
+
+CREATE UNIQUE INDEX "SmsSubmitRecord_resultEventId_key"
+ON "SmsSubmitRecord"("resultEventId");

api/prisma/schema.prisma

@@ -1760,6 +1760,8 @@ model SmsSubmitRecord {
   sequenceId            Int?
   gatewayMessageId      String?
   submitStatus          String    @default("queued")
+  resultEventId         String?   @unique
+  resultProcessedAt     DateTime?
   costUnitPrice         BigInt    @default(0)
   costAmountCents       BigInt    @default(0)
   errorCode             String?