Function init_tracing 

pub fn init_tracing(config: Option<&ObservabilityRuntimeConfig>)

Initialize OpenTelemetry tracing and Pyroscope profiling.

This function sets up:

1. A tracing subscriber with both console (fmt) and OTLP layers
2. Pyroscope continuous profiling (if enabled)

Call this early in main(), before any tracing macros are used.