feat(export): OTLP/JSON exporter for OpenTelemetry integration

[brucearctor]

Summary

Implement an OtlpJsonExporter that sends UserALE logs to any OpenTelemetry Collector via OTLP/HTTP JSON.

Motivation

OpenTelemetry is the de-facto standard for observability. OTLP support lets Flagon users send behavioral data to Grafana, Datadog, Jaeger, and any OTel-compatible backend — without building custom ingestion pipelines.

No competing behavioral analytics library (PostHog, Matomo, Plausible) speaks OTLP. This is a differentiation opportunity.

Design

• Maps Flagon log fields → OTLP LogRecord attributes using OTel semantic conventions
• Builds OTLP/JSON payloads using plain objects (zero external dependencies)
• Ships to standard OTLP HTTP receiver (port 4318, /v1/logs)
• ~150 lines of code, ~2-3 KB gzipped added to bundle

Attribute Mapping

Flagon Field	OTLP Mapping
clientTime	timeUnixNano
toolName	resource.service.name
useraleVersion	resource.telemetry.sdk.version
userId	attributes.enduser.id
sessionId	attributes.session.id
pageUrl	attributes.url.full
target	attributes.flagon.dom.target
type	attributes.flagon.event_type
logType	attributes.flagon.log_type
details	body (JSON string)

User Experience

// One config change to enable OTLP
userale.start({
  exporterType: 'otlp',
  otlpEndpoint: 'http://localhost:4318',
});

Depends On

• feat(export): introduce LogExporter interface #139 (LogExporter interface)