LSC Pre-BEST-2 Freeze & Validation Framework

This update consolidates the LSC 6.3.0 pre-BEST-2 freeze-stage framework as an unvalidated constrained phenomenological validation framework for Gallium/BEST-style neutrino anomaly analysis. It modernizes the existing archival package with the finalized GitHub freeze repository, canonical freeze documents, validation infrastructure, implementation templates, provenance manifests, audit summaries, request-for-data materials, checksums, and release discipline. The framework is preserved for future BEST-2-era comparison and validation work. It does not claim confirmed new physics, does not claim that the Gallium/BEST anomaly is solved, and does not claim sterile-neutrino exclusion. Full likelihood validation remains blocked by missing covariance matrices, extraction-level data, orientation/timestamp metadata, exposure-level information, calibration/systematics datasets, and external mappings to KATRIN, IceCube, SME/Lorentz-style constraints, solar-neutrino consistency, and standard oscillation fits.