[Good First Issue] Implement unit test coverage for internal/telemetry/metrics_exporter.go

Our core metrics_exporter.go writes raw Prometheus metrics directly onto the network wire to eliminate userspace runtime heap reflection latencies.

We need to add a comprehensive unit test suite inside internal/telemetry/metrics_exporter_test.go to validate:

1. The telemetry HTTP handler initializes without port leakage.
2. Atomic counters correctly increment on call vectors via IncrementTrafficCounters.
3. The generated text format strictly adheres to Prometheus text representation v0.0.4.

This is an isolated, high-utility task perfect for developers looking to get familiar with our zero-allocation memory footprint!