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/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,
 			},
 			{