feat(scenarios): add step title, scenario credentials, and environment context in executor

- add nullable title column to scenario steps; exposed in create/edit forms and step table
- add scenario-credential join (many-to-many with CredentialEntity) with CRUD endpoints
- expose environment URLs in code executor helpers via helpers.env and helpers.getEnvUrl()
- resolve and cache environment per run from the login step's environmentName in scheduler
- add section spacing and step table title column to ScenarioDetailPage

server/src/credential/credential.module.ts

@@ -0,0 +1,13 @@
+import { Module } from "@nestjs/common";
+import { TypeOrmModule } from "@nestjs/typeorm";
+import { CredentialEntity } from "./credential.entity";
+import { CredentialService } from "./credential.service";
+import { CredentialController } from "./credential.controller";
+
+@Module({
+  imports: [TypeOrmModule.forFeature([CredentialEntity])],
+  controllers: [CredentialController],
+  providers: [CredentialService],
+  exports: [CredentialService],
+})
+export class CredentialModule {}