treecf 0.2.4

Added

• Calibrator provenance in certificates. For calibrated-space targets the certificate's
  target.calibrator block is now structured — {embedded: false, fingerprint, type, buffer_logit} — with the fingerprint duck-read from the calibrator's own fingerprint()
  (null when absent; probcal calibrators provide one). check_certificate accepts an
  optional calibrator= keyword: when given, the report gains calibrator_match, true only
  if the fingerprints agree and re-inverting the stored calibrated bounds through the passed
  calibrator reproduces the stored raw interval.
• Calibrator provenance in batch records. BatchRecord.calibrator_fingerprint repeats the
  target calibrator's fingerprint on every row, so each JSON line stays self-contained.
• score_calibrated read-out. Counterfactual, BatchRecord, and the certificate's
  factual block now carry the calibrator's probability at the result (and at the factual)
  for calibrated targets whose calibrator exposes predict_proba; None otherwise.
  Presentational only: the engine still optimizes and verifies against the raw interval.
• Plateau-aware exactness tests. Calibrated targets on and one float above step-calibrator
  plateau levels, cross-checked against brute-force enumeration in calibrated space and
  against real probcal isotonic/centered-isotonic fits.
• probcal test matrix. New optional test extra (and probcal in the dev extra):
  7 fitted probcal calibrators x target ops x buffer levels on sklearn and LightGBM models,
  every plan re-verified through the model and calibrator; dedicated CI job with pinned
  probcal + lightgbm. src/ never imports probcal — the duck-typed protocol is unchanged.
• Docs. concepts/calibration.md gains provenance, read-out, and worked-example
  sections, and pins the guarantee that explain_batch calls interval_inverse exactly
  once per call (once per band for ladders), backed by counting tests.

Compatibility

• Strictly additive. All new dataclass fields default to None; 0.2.x batch JSON and
  certificates load with the new fields defaulted. check_certificate without calibrator=
  produces byte-identical reports to 0.2.3. Calibrators missing optional duck members
  (fingerprint, predict_proba) degrade to null/None, never an error.