Schema v2 — versioned methodology_check with named protocol IDs

[caiovicentino]

Currently methodology_check is free-form. As more entries land, we want:

• protocol_id: "causality_protocol_v1" / "causality_protocol_v2" / "lanham_2023" / ...
• protocol_sha256: hash of the protocol spec itself (versioned reproducibility)
• Tighter enums for verdict_class

Backward-compatible (v1 entries stay valid). Adds derivable trust chain: someone re-running v1 protocol gets v1 verdict; comparing to v2 verdict shows protocol drift, not signal drift.