Add new features and tests for AirGap and Time modules

- Introduced `SbomService` tasks documentation.
- Updated `StellaOps.sln` to include new projects: `StellaOps.AirGap.Time` and `StellaOps.AirGap.Importer`.
- Added unit tests for `BundleImportPlanner`, `DsseVerifier`, `ImportValidator`, and other components in the `StellaOps.AirGap.Importer.Tests` namespace.
- Implemented `InMemoryBundleRepositories` for testing bundle catalog and item repositories.
- Created `MerkleRootCalculator`, `RootRotationPolicy`, and `TufMetadataValidator` tests.
- Developed `StalenessCalculator` and `TimeAnchorLoader` tests in the `StellaOps.AirGap.Time.Tests` namespace.
- Added `fetch-sbomservice-deps.sh` script for offline dependency fetching.

docs/modules/excititor/operations/chunk-api-user-guide.md

@@ -0,0 +1,24 @@
+# Using the Chunk API
+
+Endpoint: `POST /vex/evidence/chunks`
+- Content-Type: `application/x-ndjson`
+- See schema: `docs/modules/excititor/schemas/vex-chunk-api.yaml`
+
+Response: `202 Accepted`
+```json
+{ "chunk_digest": "sha256:…", "queue_id": "uuid" }
+```
+
+Operational notes
+- Deterministic hashing: server recomputes `chunk_digest` from canonical JSON; mismatches return 400.
+- Limits: default 500 items, max 2000 (aligned with Program.cs guard).
+- Telemetry: metrics under `StellaOps.Excititor.Chunks` (see chunk-telemetry.md).
+- Headers: correlation/trace headers echoed (`X-Stella-TraceId`, `X-Stella-CorrelationId`).
+
+Example curl
+```bash
+curl -X POST https://excitor.local/vex/evidence/chunks \
+  -H "Authorization: Bearer <token>" \
+  -H "Content-Type: application/x-ndjson" \
+  --data-binary @docs/samples/excititor/chunk-sample.ndjson
+```