feat(service): add pagination to GetJobs endpoint

GetJobs now accepts page/page_size query parameters and returns JobListResponse instead of raw array. Uses in-memory pagination matching GetJobHistory pattern.

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

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

internal/service/job_service.go

@@ -82,8 +82,8 @@ func (s *JobService) SubmitJob(ctx context.Context, req *model.SubmitJobRequest)
 	return resp, nil
 }
 
-// GetJobs lists all current jobs from Slurm.
-func (s *JobService) GetJobs(ctx context.Context) ([]model.JobResponse, error) {
+// GetJobs lists all current jobs from Slurm with in-memory pagination.
+func (s *JobService) GetJobs(ctx context.Context, query *model.JobListQuery) (*model.JobListResponse, error) {
 	s.logger.Debug("slurm API request",
 		zap.String("operation", "GetJobs"),
 	)
@@ -109,11 +109,36 @@ func (s *JobService) GetJobs(ctx context.Context) ([]model.JobResponse, error) {
 		zap.Any("body", result),
 	)
 
-	jobs := make([]model.JobResponse, 0, len(result.Jobs))
+	allJobs := make([]model.JobResponse, 0, len(result.Jobs))
 	for i := range result.Jobs {
-		jobs = append(jobs, mapJobInfo(&result.Jobs[i]))
+		allJobs = append(allJobs, mapJobInfo(&result.Jobs[i]))
 	}
-	return jobs, nil
+
+	total := len(allJobs)
+	page := query.Page
+	pageSize := query.PageSize
+	if page < 1 {
+		page = 1
+	}
+	if pageSize < 1 {
+		pageSize = 20
+	}
+
+	startIdx := (page - 1) * pageSize
+	end := startIdx + pageSize
+	if startIdx > total {
+		startIdx = total
+	}
+	if end > total {
+		end = total
+	}
+
+	return &model.JobListResponse{
+		Jobs:     allJobs[startIdx:end],
+		Total:    total,
+		Page:     page,
+		PageSize: pageSize,
+	}, nil
 }
 
 // GetJob retrieves a single job by ID. If the job is not found in the active