feat(gatekeeper): add PR merge automation service

apps/api/src/gatekeeper/gatekeeper.module.ts

@@ -0,0 +1,12 @@
+import { Module } from "@nestjs/common";
+import { ConfigModule } from "@nestjs/config";
+import { GatekeeperController } from "./gatekeeper.controller";
+import { GatekeeperService } from "./gatekeeper.service";
+
+@Module({
+  imports: [ConfigModule],
+  controllers: [GatekeeperController],
+  providers: [GatekeeperService],
+  exports: [GatekeeperService],
+})
+export class GatekeeperModule {}