feat(scenarios): require environment for scenario runs

- require environmentId when creating runs in API and MCP tools

- pass selected environment data into step execution helpers

- prompt for environment selection before running scenarios in UI

server/src/scenario/scenario.service.ts

@@ -12,6 +12,7 @@ import { ScenarioRunStepEntity } from "./scenario-run-step.entity";
 import { ScenarioRunLogEntity } from "./scenario-run-log.entity";
 import { ScenarioCredentialEntity } from "./scenario-credential.entity";
 import { CredentialEntity } from "../credential/credential.entity";
+import { EnvironmentEntity } from "../environment/environment.entity";
 import { CreateScenarioDto } from "./dto/create-scenario.dto";
 import { UpdateScenarioDto } from "./dto/update-scenario.dto";
 import { CreateScenarioStepDto } from "./dto/create-scenario-step.dto";
@@ -44,6 +45,8 @@ export class ScenarioService {
     private readonly scenarioCredRepo: Repository<ScenarioCredentialEntity>,
     @InjectRepository(CredentialEntity)
     private readonly credentialRepo: Repository<CredentialEntity>,
+    @InjectRepository(EnvironmentEntity)
+    private readonly environmentRepo: Repository<EnvironmentEntity>,
   ) {}
 
   // ── Scenarios ─────────────────────────────────────────────────────────────
@@ -355,11 +358,20 @@ export class ScenarioService {
     return this.findRun(scenarioId, runId);
   }
 
-  async createRun(scenarioId: string): Promise<ScenarioRunEntity> {
+  async createRun(
+    scenarioId: string,
+    environmentId: string,
+  ): Promise<ScenarioRunEntity> {
     const scenario = await this.findOne(scenarioId);
+    const environment = await this.environmentRepo.findOneBy({
+      id: environmentId,
+    });
+    if (!environment) {
+      throw new NotFoundException(`Environment ${environmentId} not found`);
+    }
 
     const run = await this.runRepo.save(
-      this.runRepo.create({ scenarioId, status: "pending" }),
+      this.runRepo.create({ scenarioId, environmentId, status: "pending" }),
     );
 
     const stepRuns = scenario.steps.map((step, index) =>