feat: add queued status + FIFO queue ordering

- Add Queued variant to VideoStatus enum
- Trigger sets videos.status='queued' instead of staying 'pending'
- Worker sets videos.status='processing' on pickup
- list_monitor_jobs_by_status ORDER BY created_at ASC (FIFO)
- queue_position counts both 'pending' and 'queued' jobs

src/worker/job_worker.rs

@@ -294,6 +294,11 @@ impl JobWorker {
             .update_job_status(job.id, MonitorJobStatus::Running)
             .await?;
 
+        // Update video status to processing once worker picks it up
+        self.db
+            .update_video_status(&job.uuid, VideoStatus::Processing)
+            .await?;
+
         self.redis
             .update_worker_job_status(&job.uuid, job.id, "running", None, 0, total_processor_types)
             .await?;