docs(status): add v2.2.2 truth source (NO-GO + CV evidence)

[Mythmaker28]

This PR introduces a single, authoritative status file and points docs to it.

• Adds deliverables/status.json with:
  • version: v2.2.2 (balanced)
  • dataset counts (221/30/22.6% Ca)
  • modeling decision: NO-GO with strict criteria (R² ≥ 0.20; MAE < 7.81)
  • evidence block linking to lab CV metrics path.

Goal: de-confuse GO vs NO-GO and establish one source of truth that future README/Pages/scripts can read from.

Next steps (separate PRs):

• Wire README + Pages to read deliverables/status.json
• Add requirements.txt and minimal repro scripts (build table, train RF, emit metrics)
• Publish lab ZIP (shortlist, plates, protocol, SHA256) as release assets

[Mythmaker28]

Added deliverables/lab_v2_2_2/cv_metrics.json with the exact CV results (r2=-0.1803; MAE=8.49; ΔMAE=24.23%; coverage90=0.9005; ECE≈0.00045). This anchors the NO-GO call to a concrete artifact. Next, we can: (1) drop cv_predictions_uq.csv as an asset, (2) publish lab ZIP as a Release, (3) wire README/Pages to deliverables/status.json.

If you prefer a GO-on-UQ (calibration-led) framing, we can reflect that explicitly as a lab-validation GO while keeping modeling NO-GO for predictive claims. Up to you, but the criteria gate remains unmet on R²/MAE.

[Mythmaker28]

Added minimal repro guard:

• requirements.txt (pinned)
• scripts/eval_cv_metrics.py
• CI workflow .github/workflows/repro-minimal.yml

This keeps master untouched but guarantees that the NO‑GO(pred)/GO(lab) verdict is backed by a reproducible, machine-checked artifact. Next, I can prepare the draft Release v2.2.2-lab with your ZIP + SHA256, and wire README/Pages to deliverables/status.json.