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/evidence-locker/validate-bundle-prep.md

@@ -0,0 +1,23 @@
+# Validate Bundle Prep — PREP-VALIDATE-BUNDLE-187-005 (Draft)
+
+Status: Draft (2025-11-20)
+Owners: QA Guild · CLI Guild · Docs Guild
+Scope: Define validation steps for replay bundles once schemas freeze.
+
+## Validation checklist (proposed)
+- Verify archive hash vs manifest `bundle.manifest.json` (`sha256`).
+- Verify DSSE signature (if present) against trusted keys.
+- Recompute Merkle root of bundle file tree; compare to manifest.
+- Schema validation: replay records conform to `replay.record.v1`; policy export bundle conforms to `policy.export.console.v1` when included.
+- Determinism: run `stella replay` twice on same bundle and assert identical outputs (hash comparison).
+
+## Fixtures/tests
+- Place golden bundles under `tests/EvidenceLocker/Fixtures/replay/` with expected hashes and DSSE signatures.
+- CLI validation test: `stella verify --bundle <fixture>` returns exit code 0 and prints `verified: true`.
+
+## Open dependencies
+- Final schemas from Evidence Locker and Policy export contracts.
+- Trust root list for DSSE verification (Authority decision).
+
+## Handoff
+Use this prep doc for PREP-VALIDATE-BUNDLE-187-005; expand with concrete fixtures once schemas are frozen.