perf(golive/spike): binding addTrack + TS port of @dank074 media stack

Phase 1 spike: replace @dank074/discord-video-stream + node-datachannel +
node-av (1.3GB) with minimal libdatachannel N-API binding + native RTP
packetizers (H264 FU-A, RTCP SR/NACK, pacer) + pure-TS GoLive stack.

Binding v0.4: addTrack (m=audio/video SDP), TrackWrap w/ setPacketizer +
sendFrame (raw RTP to transport) + addTimestamp — verified by two-peer
handshake emitting SDP with audio(opus 120)+video(H264 101) and 8-frame
RTP roundtrip.

TS layer (src/goLive/, 21 files): CodecPayloadType, VoiceOpCodes,
GatewayOpCodes, utils, BaseMediaConnection (voice WS + DAVE + heartbeat),
VoiceConnection, StreamConnection, Streamer, WebRtcWrapper (SDP mungling,
DAVE encrypt, packetizer chain), BaseMediaStream (pacing/sync), VideoStream,
AudioStream, Demuxer (ffmpeg-spawn NUT/AnnexB, no node-av 114M binary),
Encoders, prepareStream/playStream.

Integration: screenShareController.ts now imports from ../../goLive/index.js —
prepareStream(prepared, ...) + playStream(prepared, streamer, {...}).

Tests: tests/goLive-port.test.ts (8/8 pass). tsc --noEmit clean. biome clean.

services/discord-gateway/src/goLive/VoiceOpCodes.ts

@@ -0,0 +1,38 @@
+/** Discord voice WebSocket opcodes — ported from @dank074/discord-video-stream. */
+export enum VoiceOpCodes {
+  IDENTIFY = 0,
+  SELECT_PROTOCOL = 1,
+  READY = 2,
+  HEARTBEAT = 3,
+  SELECT_PROTOCOL_ACK = 4,
+  SPEAKING = 5,
+  HEARTBEAT_ACK = 6,
+  RESUME = 7,
+  HELLO = 8,
+  RESUMED = 9,
+  CLIENTS_CONNECT = 11,
+  VIDEO = 12,
+  CLIENT_DISCONNECT = 13,
+  SESSION_UPDATE = 14,
+  MEDIA_SINK_WANTS = 15,
+  VOICE_BACKEND_VERSION = 16,
+  CHANNEL_OPTIONS_UPDATE = 17,
+  FLAGS = 18,
+  SPEED_TEST = 19,
+  PLATFORM = 20,
+  DAVE_PREPARE_TRANSITION = 21,
+  DAVE_EXECUTE_TRANSITION = 22,
+  DAVE_TRANSITION_READY = 23,
+  DAVE_PREPARE_EPOCH = 24,
+  MLS_INVALID_COMMIT_WELCOME = 31,
+}
+
+/** Binary voice WebSocket opcodes (DAVE / MLS). */
+export enum VoiceOpCodesBinary {
+  MLS_EXTERNAL_SENDER = 25,
+  MLS_KEY_PACKAGE = 26,
+  MLS_PROPOSALS = 27,
+  MLS_COMMIT_WELCOME = 28,
+  MLS_ANNOUNCE_COMMIT_TRANSITION = 29,
+  MLS_WELCOME = 30,
+}