Migrate Splunk logging to OpenTelemetry

[chrisgroks]

Overview

Migrate from custom Splunk logger to OpenTelemetry for modern, vendor-neutral observability.

Benefits

• Industry standard observability
• Vendor-neutral (works with Splunk, Datadog, etc.)
• Built-in distributed tracing
• Better correlation and context propagation
• Rich ecosystem of instrumentation

Implementation

• Replace custom-splunk-logger.js with OpenTelemetry SDK
• Configure OTLP exporter for Splunk
• Add automatic instrumentation for Express
• Implement proper trace context propagation
• Update tests for new telemetry format

Prerequisites

• Issue Migrate Splunk logging to OpenTelemetry #2 (clean up) should be completed first
• Existing tests provide safety net

See documentation/SPLUNK_LOGGING_IMPROVEMENT_PLAN.md for migration plan.