feat(server): add hls playlist hint (#29150)

* add playlist hint

* update api

* unused import

* update crf in tests

server/src/services/transcoding.service.ts

@@ -5,6 +5,7 @@ import {
   HLS_BACKPRESSURE_PAUSE_SEGMENTS,
   HLS_BACKPRESSURE_RESUME_SEGMENTS,
   HLS_CLEANUP_INTERVAL_MS,
+  HLS_CRF,
   HLS_INACTIVITY_TIMEOUT_MS,
   HLS_LEASE_DURATION_MS,
   HLS_SEGMENT_DURATION,
@@ -221,6 +222,7 @@ export class TranscodingService extends BaseService {
           targetResolution: String(variant.resolution),
           maxBitrate: `${Math.round(variant.bitrate / 1000)}k`,
           gopSize: gop,
+          crf: HLS_CRF[variant.codec],
         },
         this.videoInterfaces,
         { strictGop: true, lowLatency: true },