Function init_logging 

pub fn init_logging(config: &LoggingConfig) -> LoggingInitResult

Initializes global tracing subscriber using Aster’s standard runtime logging behavior.

File writer failures fall back to stdout and are reported through LoggingInitResult::warning. RUST_LOG takes precedence over LoggingConfig::level and also produces a warning so startup logs can surface which setting actually won; an invalid RUST_LOG value warns and falls back to the configured level instead of being silently ignored. Installing a second global subscriber (embedded runtimes, shared test processes) keeps the existing subscriber and warns rather than panicking.