fix(homekit): fix HKSV recording by correcting HDS protocol and adding GOP buffering

The HKSV recording was failing because:
1. The dataSend.data message structure was wrong - `packets` was a flat integer
   instead of an array of objects with `data` and `metadata` fields matching
   the HAP-NodeJS specification
2. Each video/audio frame was sent as a separate mediaFragment, but Home Hub
   expects GOP-based fragments (~2-4 seconds of accumulated data)
3. Large fragments were not chunked (max 256 KiB per chunk)

Changes:
- Fix HDS dataSend.data message structure to use proper packets array with
  nested data/metadata (dataType, dataSequenceNumber, dataChunkSequenceNumber,
  isLastDataChunk, dataTotalSize)
- Add 256 KiB chunking for large media fragments
- Buffer moof+mdat pairs in hksvConsumer and flush on keyframe boundaries
  (GOP-based fragmentation)
- Pre-start consumer at pair-verify for instant init segment delivery
- Add write-response support to HAP PUT handler for ch131 DataStream setup
- Fix HAP service linking to match HAP-NodeJS reference
- Add default SelectedCameraRecordingConfiguration (ch209) value
- Start continuous motion generator at pair-verify with dedup protection

pkg/hap/camera/accessory.go

@@ -40,10 +40,8 @@ func NewHKSVAccessory(manuf, model, name, serial, firmware string) *hap.Accessor
 	}
 	acc.InitIID()
 
-	// CameraOperatingMode links to RTPStreamManagement and RecordingManagement
-	operatingMode.Linked = []int{int(rtpStream.IID), int(recordingMgmt.IID)}
-	// CameraEventRecordingManagement links to DataStreamManagement and MotionSensor
-	recordingMgmt.Linked = []int{int(dataStreamMgmt.IID), int(motionSensor.IID)}
+	// HAP-NodeJS: only RecordingManagement links to DataStreamManagement
+	recordingMgmt.Linked = []int{int(dataStreamMgmt.IID)}
 
 	return acc
 }
@@ -71,10 +69,8 @@ func NewHKSVDoorbellAccessory(manuf, model, name, serial, firmware string) *hap.
 	}
 	acc.InitIID()
 
-	// CameraOperatingMode links to RTPStreamManagement and RecordingManagement
-	operatingMode.Linked = []int{int(rtpStream.IID), int(recordingMgmt.IID)}
-	// CameraEventRecordingManagement links to DataStreamManagement, MotionSensor, and Doorbell
-	recordingMgmt.Linked = []int{int(dataStreamMgmt.IID), int(motionSensor.IID), int(doorbell.IID)}
+	// HAP-NodeJS: only RecordingManagement links to DataStreamManagement
+	recordingMgmt.Linked = []int{int(dataStreamMgmt.IID)}
 
 	return acc
 }

pkg/hap/camera/services_hksv.go

@@ -104,6 +104,49 @@ func ServiceCameraEventRecordingManagement() *hap.Service {
 		},
 	})
 
+	// Default selected recording configuration (Home Hub expects this to persist)
+	val209, _ := tlv8.MarshalBase64(SelectedCameraRecordingConfiguration{
+		GeneralConfig: SupportedCameraRecordingConfiguration{
+			PrebufferLength:     4000,
+			EventTriggerOptions: 0x01, // motion
+			MediaContainerConfigurations: MediaContainerConfigurations{
+				MediaContainerType: 0,
+				MediaContainerParameters: MediaContainerParameters{
+					FragmentLength: 4000,
+				},
+			},
+		},
+		VideoConfig: SupportedVideoRecordingConfiguration{
+			CodecConfigs: []VideoRecordingCodecConfiguration{
+				{
+					CodecType: VideoCodecTypeH264,
+					CodecParams: VideoRecordingCodecParameters{
+						ProfileID:      VideoCodecProfileHigh,
+						Level:          VideoCodecLevel40,
+						Bitrate:        2000,
+						IFrameInterval: 4000,
+					},
+					CodecAttrs: VideoCodecAttributes{Width: 1920, Height: 1080, Framerate: 30},
+				},
+			},
+		},
+		AudioConfig: SupportedAudioRecordingConfiguration{
+			CodecConfigs: []AudioRecordingCodecConfiguration{
+				{
+					CodecType: AudioRecordingCodecTypeAACLC,
+					CodecParams: []AudioRecordingCodecParameters{
+						{
+							Channels:        1,
+							BitrateMode:     []byte{AudioCodecBitrateVariable},
+							SampleRate:      []byte{AudioRecordingSampleRate24Khz},
+							MaxAudioBitrate: []uint32{64},
+						},
+					},
+				},
+			},
+		},
+	})
+
 	return &hap.Service{
 		Type: "204",
 		Characters: []*hap.Character{
@@ -134,7 +177,7 @@ func ServiceCameraEventRecordingManagement() *hap.Service {
 			{
 				Type:   TypeSelectedCameraRecordingConfiguration,
 				Format: hap.FormatTLV8,
-				Value:  "",
+				Value:  val209,
 				Perms:  hap.EVPRPW,
 			},
 			{

pkg/hap/hds/protocol.go

@@ -163,27 +163,59 @@ func (s *Session) WriteRequest(protocol, topic string, body map[string]any) (int
 	return id, s.WriteMessage(header, body)
 }
 
+// maxChunkSize is the maximum data chunk size for HDS media transfer (256 KiB)
+const maxChunkSize = 0x40000
+
 // SendMediaInit sends the fMP4 initialization segment (ftyp+moov)
 func (s *Session) SendMediaInit(streamID int, initData []byte) error {
-	return s.WriteEvent(ProtoDataSend, TopicData, map[string]any{
-		"streamId": streamID,
-		"packets":  1,
-		"type":     "mediaInitialization",
-		"data":     initData,
-	})
+	return s.sendMediaData(streamID, "mediaInitialization", initData, 1)
 }
 
-// SendMediaFragment sends an fMP4 fragment (moof+mdat)
+// SendMediaFragment sends an fMP4 fragment (moof+mdat), splitting into chunks if needed
 func (s *Session) SendMediaFragment(streamID int, fragment []byte, sequence int) error {
-	return s.WriteEvent(ProtoDataSend, TopicData, map[string]any{
-		"streamId":               streamID,
-		"packets":                1,
-		"type":                   "mediaFragment",
-		"data":                   fragment,
-		"dataSequenceNumber":     sequence,
-		"isLastDataChunk":        true,
-		"dataChunkSequenceNumber": 0,
-	})
+	return s.sendMediaData(streamID, "mediaFragment", fragment, sequence)
+}
+
+// sendMediaData sends media data with proper HAP-NodeJS compatible packet structure.
+// Large data is split into chunks of maxChunkSize bytes.
+func (s *Session) sendMediaData(streamID int, dataType string, data []byte, sequence int) error {
+	totalSize := len(data)
+	chunkSeq := 1
+
+	for offset := 0; offset < totalSize; offset += maxChunkSize {
+		end := offset + maxChunkSize
+		if end > totalSize {
+			end = totalSize
+		}
+		chunk := data[offset:end]
+		isLast := end >= totalSize
+
+		metadata := map[string]any{
+			"dataType":                dataType,
+			"dataSequenceNumber":      sequence,
+			"dataChunkSequenceNumber": chunkSeq,
+			"isLastDataChunk":         isLast,
+		}
+		if chunkSeq == 1 {
+			metadata["dataTotalSize"] = totalSize
+		}
+
+		body := map[string]any{
+			"streamId": streamID,
+			"packets": []any{
+				map[string]any{
+					"data":     chunk,
+					"metadata": metadata,
+				},
+			},
+		}
+
+		if err := s.WriteEvent(ProtoDataSend, TopicData, body); err != nil {
+			return err
+		}
+		chunkSeq++
+	}
+	return nil
 }
 
 // Run processes incoming HDS messages in a loop