fix(scenario-runner): preserve session on failed runs

- failStepRun was calling closeBrowserHandle immediately, removing the
  handle before maybePreserveSession could read it in the finally block
- delegate browser lifecycle to maybePreserveSession for both pass and
  fail paths so saveSession=true is honoured regardless of run outcome

server/src/scenario/scenario-scheduler.service.ts

@@ -353,7 +353,9 @@ export class ScenarioSchedulerService {
 
     this.logger.log(`Run #${stepRun.runId}: remaining steps cancelled`);
 
-    await this.closeBrowserHandle(stepRun.runId);
+    // Don't close the browser here — maybePreserveSession (called from
+    // processRunToCompletion's finally block) will either preserve it as a
+    // session (saveSession=true) or close it (saveSession=false).
     await this.runRepo.update(stepRun.runId, { status: "fail" });
     this.logger.log(`Run #${stepRun.runId} → fail`);
   }