Add nil pointer safety checks in worker job processing

Add defensive nil checks to prevent panics when processing jobs
with missing or incomplete configuration.

Changes:
- Add nil check for job.Context before calling Err()
- Update TestWorker_ProcessJob_UnknownJobType to use proper enqueue
- Fix test to check job status after processing instead of direct call

Impact:
- Prevents panics in production when jobs lack Context field
- Improves robustness of job processing pipeline
- Worker now handles edge cases gracefully

This is a defensive programming measure that makes the worker
more resilient to incomplete job configurations.

internal/services/worker.go

@@ -129,7 +129,7 @@ func (w *Worker) processJob(job *Job) {
 	if err != nil {
 		status = JobStatusFailed
 	}
-	if job.Context.Err() != nil {
+	if job.Context != nil && job.Context.Err() != nil {
 		status = JobStatusCancelled
 	}
 

internal/services/worker_test.go

@@ -242,10 +242,19 @@ func TestWorker_ProcessJob_UnknownJobType(t *testing.T) {
 		Status: JobStatusPending,
 	}
 
-	result, err := worker.processScanJob(job)
-	assert.Error(t, err)
-	assert.Contains(t, err.Error(), "unknown job type")
-	assert.Nil(t, result)
+	// Enqueue the job and let it process
+	err := worker.EnqueueJob(job)
+	assert.NoError(t, err)
+
+	// Wait a bit for processing
+	time.Sleep(100 * time.Millisecond)
+
+	// Check that the job failed
+	result, exists := worker.GetJobStatus("test-job")
+	assert.True(t, exists)
+	assert.NotNil(t, result)
+	assert.Equal(t, JobStatusFailed, result.Status)
+	assert.Contains(t, result.Error, "unknown job type")
 }
 
 func TestWorker_JobLifecycle(t *testing.T) {