Constant MAX_CONCURRENT_CLI_INSTANCES 

pub const MAX_CONCURRENT_CLI_INSTANCES: usize = 16;

Maximum number of CLI instances running simultaneously.

Limits the counting semaphore in crate::lock to prevent memory overload when multiple parallel v1.0.75 (G18 solution): removed the rigid 4-slot ceiling. The adaptive calculate_safe_concurrency function in crate::locknow reports the dynamic limit. This constant is preserved as a *legacy fallback* when the dynamic calculation cannot be performed (e.g. whensysinfocannot read/proc/meminfo`).

Operators should prefer passing --max-concurrency explicitly OR letting the runtime compute the limit. The default ceiling is intentionally higher (16) so the legacy 4-slot hard cap does not silently reappear.