Add unit tests for SBOM ingestion and transformation

- Implement `SbomIngestServiceCollectionExtensionsTests` to verify the SBOM ingestion pipeline exports snapshots correctly.
- Create `SbomIngestTransformerTests` to ensure the transformation produces expected nodes and edges, including deduplication of license nodes and normalization of timestamps.
- Add `SbomSnapshotExporterTests` to test the export functionality for manifest, adjacency, nodes, and edges.
- Introduce `VexOverlayTransformerTests` to validate the transformation of VEX nodes and edges.
- Set up project file for the test project with necessary dependencies and configurations.
- Include JSON fixture files for testing purposes.

docs/modules/attestor/ttl-validation.md

@@ -39,3 +39,9 @@ If the helper script cannot be used:
 ## Ownership
 - Primary: Attestor Service Guild.
 - Partner: QA Guild (observes TTL metrics, confirms evidence archiving).
+
+## 2025-11-03 validation summary
+- **Stack:** `mongod` 7.0.5 (tarball) + `mongosh` 2.0.2, `redis-server` 7.2.4 (source build) running on localhost without Docker.
+- **Mongo results:** `dedupe` TTL index (`ttlAt`, `expireAfterSeconds: 0`) confirmed; document inserted with 20 s TTL expired automatically after ~80 s (expected allocator sweep). Evidence: `docs/modules/attestor/evidence/2025-11-03-mongo-ttl-validation.txt`.
+- **Redis results:** Key `attestor:ttl:live:bundle:validation` set with 45 s TTL reached `TTL=-2` after ~47 s confirming expiry propagation. Evidence: `docs/modules/attestor/evidence/2025-11-03-redis-ttl-validation.txt`.
+- **Notes:** Local binaries built/run to accommodate sandbox without Docker; services shut down after validation.