Function mirror_legacy_env 

pub fn mirror_legacy_env() -> Vec<String>

Mirror every ATLAS_* variable onto its AVAROK_* name when the new name is unset. Returns the mirrored keys (new names). Must run before any thread is spawned; call it first thing in main.

An AVAROK_* value already present always wins: an operator who sets the new name explicitly is never overridden by a stale legacy export.

Example

// First statement of `main`, before any runtime, logging or thread init.
let mirrored = avarok_core::env_compat::mirror_legacy_env();
if !mirrored.is_empty() {
    eprintln!("mirrored {} legacy variables", mirrored.len());
}