Add determinism tests for verdict artifact generation and update SHA256 sums script

- Implemented comprehensive tests for verdict artifact generation to ensure deterministic outputs across various scenarios, including identical inputs, parallel execution, and change ordering.
- Created helper methods for generating sample verdict inputs and computing canonical hashes.
- Added tests to validate the stability of canonical hashes, proof spine ordering, and summary statistics.
- Introduced a new PowerShell script to update SHA256 sums for files, ensuring accurate hash generation and file integrity checks.

docs/vex/consensus-json.md

@@ -1,6 +1,47 @@
-# Archived: VEX Consensus JSON
+# VEX Consensus JSON (Payload Reference)
 
-This document was consolidated during docs cleanup.
+This document describes the *shape* of consensus records returned by consensus APIs and exported in Offline Kit snapshots. Field names and structure may vary slightly by gateway serialization, but the semantic contract is stable.
 
-- Canonical guide: `docs/16_VEX_CONSENSUS_GUIDE.md`
-- Module dossier: `docs/modules/vex-lens/architecture.md`
+## Consensus Record (Conceptual)
+
+```json
+{
+  "artifact": "pkg:rpm/redhat/openssl@3.0.9",
+  "advisory": "CVE-2025-13579",
+  "status": "not_affected",
+  "confidence": 0.92,
+  "issued_at": "2025-08-30T12:05:00Z",
+  "consensus_digest": "sha256:…",
+  "derived_from": [
+    {
+      "source_digest": "sha256:…",
+      "issuer": "vendor:redhat",
+      "status": "not_affected",
+      "timestamp": "2025-08-30T12:00:00Z",
+      "trust": { "tier": "vendor", "weight": 1.0 },
+      "verification": { "signature": "verified" }
+    }
+  ],
+  "conflicts": [
+    {
+      "source_digest": "sha256:…",
+      "issuer": "vendor:upstream",
+      "status": "affected",
+      "timestamp": "2025-08-29T00:00:00Z",
+      "trust": { "tier": "vendor", "weight": 0.8 }
+    }
+  ]
+}
+```
+
+## Determinism Rules
+
+- Timestamps are UTC ISO-8601.
+- Arrays (`derived_from`, `conflicts`) are in a stable order (typically the evaluation sort order).
+- `consensus_digest` is computed over canonical, deterministic JSON bytes for the record (or over an equivalent canonical projection).
+
+## Related Docs
+
+- Algorithm overview: `docs/vex/consensus-algorithm.md`
+- Endpoints: `docs/vex/consensus-api.md`
+- Module details: `docs/modules/vex-lens/architecture.md`