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/scenario/scenario.controller.ts

@@ -16,6 +16,7 @@ import { CreateScenarioDto } from "./dto/create-scenario.dto";
 import { UpdateScenarioDto } from "./dto/update-scenario.dto";
 import { CreateScenarioStepDto } from "./dto/create-scenario-step.dto";
 import { UpdateScenarioStepDto } from "./dto/update-scenario-step.dto";
+import { AddScenarioCredentialDto } from "./dto/add-scenario-credential.dto";
 import { PaginationQueryDto } from "./dto/pagination-query.dto";
 import { ScenarioOrderBy } from "./scenario.service";
 import { RunsQueryDto } from "./dto/runs-query.dto";
@@ -140,6 +141,40 @@ export class ScenarioController {
     return this.scenarioService.removeStep(id, stepId);
   }
 
+  // ── Credentials ───────────────────────────────────────────────────────────
+
+  @Get(":id/credentials")
+  @ApiOperation({ summary: "List credentials assigned to a scenario" })
+  @ApiResponse({ status: 200 })
+  @ApiResponse({ status: 404, description: "Scenario not found" })
+  findScenarioCredentials(@Param("id", ParseIntPipe) id: number) {
+    return this.scenarioService.findScenarioCredentials(id);
+  }
+
+  @Post(":id/credentials")
+  @ApiOperation({ summary: "Add a credential to a scenario with an alias" })
+  @ApiResponse({ status: 201, description: "Credential added" })
+  @ApiResponse({ status: 404, description: "Scenario or credential not found" })
+  @ApiResponse({ status: 409, description: "Alias already used in this scenario" })
+  addScenarioCredential(
+    @Param("id", ParseIntPipe) id: number,
+    @Body() dto: AddScenarioCredentialDto,
+  ) {
+    return this.scenarioService.addScenarioCredential(id, dto);
+  }
+
+  @Delete(":id/credentials/:scCredId")
+  @HttpCode(204)
+  @ApiOperation({ summary: "Remove a credential from a scenario" })
+  @ApiResponse({ status: 204 })
+  @ApiResponse({ status: 404, description: "Scenario or credential assignment not found" })
+  removeScenarioCredential(
+    @Param("id", ParseIntPipe) id: number,
+    @Param("scCredId", ParseIntPipe) scCredId: number,
+  ) {
+    return this.scenarioService.removeScenarioCredential(id, scCredId);
+  }
+
   // ── Runs ──────────────────────────────────────────────────────────────────
 
   @Get(":id/runs")