preload

Profile-guided preload of the compiler working set. Returns true on a TRAINING launch — preload skipped entirely, so the compiler build loads exactly the true working set for recordWorkingSet to capture; preloading first would make the working set indistinguishable from dead classes. Training is every launch with nothing to replay: no recorded list, a list stamped with another kotlin version, or mcp.preload=false — the only lever that retrains a list the stamp still calls current, for a classpath change the kotlin version cannot see. False only where a list really was preloaded. Idempotent.