feat(service): pass work directory to Slurm job submission

Add WorkDir to SubmitJobRequest and pass it as CurrentWorkingDirectory to Slurm REST API. Fixes Slurm 500 error when working directory is not specified.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/service/job_service.go

@@ -32,6 +32,9 @@ func (s *JobService) SubmitJob(ctx context.Context, req *model.SubmitJobRequest)
 		Qos:       strToPtrOrNil(req.QOS),
 		Name:      strToPtrOrNil(req.JobName),
 	}
+	if req.WorkDir != "" {
+		jobDesc.CurrentWorkingDirectory = &req.WorkDir
+	}
 	if req.CPUs > 0 {
 		jobDesc.MinimumCpus = slurm.Ptr(req.CPUs)
 	}