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/runbooks/replay_ops_prep_187_004.md

@@ -0,0 +1,20 @@
+# Replay Ops Runbook Prep — PREP-RUNBOOK-REPLAY-187-004 (Draft)
+
+Status: Draft (2025-11-20)
+Owners: Docs Guild · Ops Guild
+Scope: Capture required sections for the replay operations runbook once APIs are finalized.
+
+## Runbook sections to include
+1) **Prechecks**: confirm trust roots, air-gap status, Evidence Locker availability, and bundle integrity (`sha256`, DSSE verification).
+2) **Ingestion**: steps to POST replay records to Evidence Locker (`/replay/records`), expected responses, retry/backoff guidance.
+3) **Verification**: CLI commands (`stella verify --bundle`), Attestor verification call once available, interpreting results.
+4) **Replay/Compare**: `stella replay` and `stella diff` workflows, deterministic output locations, common failure modes.
+5) **Observability**: log/metric names to watch (to be filled after Evidence Locker/CLI finalize telemetry).
+6) **Escalation**: contacts for Scanner/CLI/Attestor/Evidence Locker guilds.
+
+## Dependencies
+- Replay payload schema (`docs/modules/evidence-locker/replay-payload-contract.md`).
+- CLI and Attestor prep docs for command/API details.
+
+## Handoff
+When APIs finalize, merge this content into `docs/runbooks/replay_ops.md` and retire this prep stub.