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.

.gitea/workflows/build-test-deploy.yml

@@ -58,12 +58,20 @@ jobs:
       PUBLISH_DIR: ${{ github.workspace }}/artifacts/publish/webservice
       AUTHORITY_PUBLISH_DIR: ${{ github.workspace }}/artifacts/publish/authority
       TEST_RESULTS_DIR: ${{ github.workspace }}/artifacts/test-results
+      STELLAOPS_TEST_MONGO_URI: ${{ secrets.STELLAOPS_TEST_MONGO_URI || vars.STELLAOPS_TEST_MONGO_URI }}
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
+      - name: Ensure Mongo test URI configured
+        run: |
+          if [ -z "${STELLAOPS_TEST_MONGO_URI:-}" ]; then
+            echo "::error::STELLAOPS_TEST_MONGO_URI must be provided via repository secrets or variables for Graph Indexer integration tests."
+            exit 1
+          fi
+
       - name: Verify policy scope configuration
         run: python3 scripts/verify-policy-scopes.py