feat: enforce signature-scoped drainage authorization before SMS submission

api/prisma/migrations/20260910130000_drainage_send_gate/migration.sql

@@ -0,0 +1,30 @@
+ALTER TABLE "SmsMessageRecord" ADD COLUMN "drainageGate" JSONB;
+ALTER TABLE "SmsSubmitRecord" ADD COLUMN "drainageGate" JSONB;
+ALTER TABLE "SmsMessageRecord" ADD COLUMN "drainageReceiptPending" BOOLEAN NOT NULL DEFAULT false;
+CREATE INDEX "SmsMessageRecord_drainage_receipt_pending" ON "SmsMessageRecord" ("updatedAt") WHERE "drainageReceiptPending" = true;
+CREATE TABLE "SmsDrainageDecision" (
+  "id" TEXT PRIMARY KEY,
+  "messageRecordId" TEXT NOT NULL,
+  "decidedAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "snapshot" JSONB NOT NULL
+);
+CREATE INDEX "SmsDrainageDecision_messageRecordId_decidedAt_idx" ON "SmsDrainageDecision" ("messageRecordId", "decidedAt");
+
+CREATE OR REPLACE FUNCTION drainage_authorization_lock() RETURNS trigger LANGUAGE plpgsql AS $$
+BEGIN
+  IF TG_OP = 'UPDATE' AND OLD."signatureId" IS DISTINCT FROM NEW."signatureId" THEN
+    PERFORM pg_advisory_xact_lock(hashtextextended(value, 910))
+      FROM unnest(ARRAY[OLD."signatureId", NEW."signatureId"]) AS ids(value) ORDER BY value;
+    RETURN NEW;
+  END IF;
+  IF TG_OP = 'DELETE' THEN
+    PERFORM pg_advisory_xact_lock(hashtextextended(OLD."signatureId", 910));
+    RETURN OLD;
+  END IF;
+  PERFORM pg_advisory_xact_lock(hashtextextended(NEW."signatureId", 910));
+  RETURN NEW;
+END $$;
+CREATE TRIGGER drainage_material_authorization_lock BEFORE INSERT OR UPDATE OR DELETE ON "SmsDrainageInfo"
+FOR EACH ROW EXECUTE FUNCTION drainage_authorization_lock();
+CREATE TRIGGER drainage_report_authorization_lock BEFORE INSERT OR UPDATE OR DELETE ON "ChannelSignatureReportTask"
+FOR EACH ROW EXECUTE FUNCTION drainage_authorization_lock();