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/core/db/postgres_db.rs

@@ -194,6 +194,7 @@ pub enum VideoStatus {
     Unregistered,
     Registered,
     Pending,
+    Queued,
     Processing,
     Processed,
     Indexed,
@@ -208,6 +209,7 @@ impl VideoStatus {
             VideoStatus::Unregistered => "unregistered",
             VideoStatus::Registered => "registered",
             VideoStatus::Pending => "pending",
+            VideoStatus::Queued => "queued",
             VideoStatus::Processing => "processing",
             VideoStatus::Processed => "processed",
             VideoStatus::Indexed => "indexed",
@@ -222,6 +224,7 @@ impl VideoStatus {
             "unregistered" => Some(VideoStatus::Unregistered),
             "registered" => Some(VideoStatus::Registered),
             "pending" => Some(VideoStatus::Pending),
+            "queued" => Some(VideoStatus::Queued),
             "processing" => Some(VideoStatus::Processing),
             "processed" => Some(VideoStatus::Processed),
             "indexed" => Some(VideoStatus::Indexed),
@@ -2030,7 +2033,7 @@ sqlx::query(
             &format!(
                 r#"
                 SELECT id, uuid, video_path, status, current_processor, progress_total, progress_current, error_count, last_error, started_at::TEXT, updated_at::TEXT, created_at::TEXT, processors, completed_processors, failed_processors, video_id
-                FROM {} WHERE status = $1 ORDER BY created_at DESC
+                FROM {} WHERE status = $1 ORDER BY created_at ASC
                 "#,
                 table
             )