Named threshold preset — a calibration tier, independent of
metric. The concrete f64 cutoff is resolved per metric via
ThresholdPreset::threshold (the same tier maps to a different
number for cyclomatic vs cognitive scores).
Default CRAP cutoff for the cognitive metric — gates at the
Acceptable → Moderate risk boundary; the balanced tier for typical
codebases. Cyclomatic equivalent: DEFAULT_THRESHOLD_CYCLOMATIC.
Lenient CRAP cutoff for the cognitive metric — gates at the
Moderate → High risk boundary; for legacy or transitional code.
Cyclomatic equivalent: LENIENT_THRESHOLD_CYCLOMATIC.
Strict CRAP cutoff for the cognitive metric — gates at the
Low → Acceptable risk boundary; for high-quality or safety-critical
code. Cyclomatic equivalent: STRICT_THRESHOLD_CYCLOMATIC.
Strict CRAP cutoff for the cyclomatic metric. Currently flat-
equal to the cognitive strict value; the constant is retained so a
future per-metric recalibration is a one-line change.