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/airgap/time-anchor-verification-gap.md

@@ -0,0 +1,21 @@
+# Time Anchor Verification Gap (AIRGAP-TIME-57-001 follow-up)
+
+## Status (2025-11-20)
+- Parser: stubbed for Roughtime/RFC3161 with deterministic digest + derived anchor time.
+- Staleness: calculator + budgets landed; loader accepts hex fixtures.
+- Verification: pipeline exists (`TimeVerificationService`) with stub verifiers; still needs real crypto using guild-provided trust roots.
+
+## What’s missing
+- Roughtime parser: parse signed responses, extract `timestamp`, `radius`, `verifier` public key; verify signature.
+- RFC3161 parser: decode ASN.1 TimeStampToken, verify signer chain against provided trust roots, extract nonce/ts.
+- Trust roots: final format (JWK vs PEM) and key IDs to align with `TrustRootConfig`/Time service.
+
+## Proposed plan
+1) Receive finalized token format + trust-root bundle from Time Guild.
+2) Implement format-specific verifiers with validating tests using provided fixtures.
+3) Expose `/api/v1/time/status` returning anchor metadata + staleness; wire telemetry counters/alerts per sealed diagnostics doc.
+
+## Owners
+- AirGap Time Guild (format decision + trust roots)
+- AirGap Importer Guild (bundle delivery of anchors)
+- Observability Guild (telemetry wiring)