LAB03: publish spatial cross-validation

[EHDataAI]

Summary

Publishes LAB03 — Spatial Cross-Validation in the Mining Geospatial Analytics portfolio.

Public scope

• recruiter-facing executed notebook
• reproducible experiment and aggregation scripts
• reusable spatial-validation utilities
• persisted synthetic analytical results
• automated tests
• updated public environment
• updated portfolio documentation and roadmap

Validation

• Full public test suite: 31 passed
• pre-commit: passed
• Gitleaks: passed
• synthetic data only
• no confidential exploration data
• notebook-build and release tooling excluded from public scope