Implements OtelTracer as ITracer replacement for SentryTracer. Uses @opentelemetry/api's trace.getTracer + startActiveSpan, maps span.op to a span attribute, catches exceptions via recordException + setStatus(ERROR), and filters null attribute values. Five Vitest tests covering name/attributes, nesting, exception recording, status mapping, and null filtering. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>