perf(playout): parallelize playlist validation with dedup and worker pool

.gitea/workflows/cd.yml

@@ -270,8 +270,8 @@ jobs:
               echo "Playout is healthy"
               break
             fi
-            echo "Playout not ready yet (attempt $i/6), waiting 10s..."
-            sleep 10
+            echo "Playout not ready yet (attempt $i/6), waiting 20s..."
+            sleep 20
           done
           if ! docker exec linearvoid-playout curl -sf http://localhost:8081/health; then
             echo "Playout failed to become healthy after 6 attempts"