feat: add per-job context to global Pino logger

[karan-dhir]

Summary

Closes #1336.

Sets jobId and roomName on the global Pino logger when a job starts, so all SDK-internal logs (TTS/STT metrics, speech events, AgentSession lifecycle) include per-job fields on every log line. Context is cleared after shutdown callbacks complete to prevent stale fields leaking to the next job.

This enables filtering all logs for a single call in log aggregation tools:

-- NewRelic
SELECT * FROM Log WHERE jobId = 'AJ_xxx' SINCE 1 hour ago

-- Datadog
jobId:AJ_xxx

-- Grafana/Loki
{jobId="AJ_xxx"}

Changes

• agents/src/log.ts: Add setJobContext() — creates a Pino child logger with the provided fields, storing the base logger so it can be restored. Also updates enableOtelLogging() to keep the base logger in sync.
• agents/src/job.ts: Call setJobContext({ jobId, roomName }) in the JobContext constructor.
• agents/src/ipc/job_proc_lazy_main.ts: Call setJobContext({}) after shutdown callbacks to clear context before the next job.

Why this is safe

LiveKit workers process one job at a time (single-threaded, sequential dispatch), so mutating the global logger has no concurrency risk.

Testing

Verified locally that Pino child logger correctly adds fields to all subsequent log() calls and that restoring the base logger cleanly removes them:

BEFORE: {"msg":"TTS metrics"}
AFTER:  {"jobId":"AJ_xxx","roomName":"room_abc","msg":"TTS metrics"}
CLEAR:  {"msg":"next job log"}  // no stale fields

[changeset-bot]

🦋 Changeset detected

Latest commit: 2b543e4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 26 packages

Name	Type
@livekit/agents	Major
@livekit/agents-plugin-anam	Major
@livekit/agents-plugin-assemblyai	Major
@livekit/agents-plugin-baseten	Major
@livekit/agents-plugin-bey	Major
@livekit/agents-plugin-cartesia	Major
@livekit/agents-plugin-cerebras	Major
@livekit/agents-plugin-deepgram	Major
@livekit/agents-plugin-elevenlabs	Major
@livekit/agents-plugin-google	Major
@livekit/agents-plugin-hedra	Major
@livekit/agents-plugin-inworld	Major
@livekit/agents-plugin-lemonslice	Major
@livekit/agents-plugin-livekit	Major
@livekit/agents-plugin-mistral	Major
@livekit/agents-plugin-neuphonic	Major
@livekit/agents-plugin-openai	Major
@livekit/agents-plugin-phonic	Major
@livekit/agents-plugin-resemble	Major
@livekit/agents-plugin-rime	Major
@livekit/agents-plugin-runway	Major
@livekit/agents-plugin-sarvam	Major
@livekit/agents-plugin-silero	Major
@livekit/agents-plugins-test	Major
@livekit/agents-plugin-trugen	Major
@livekit/agents-plugin-xai	Major

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