Add tests for SBOM generation determinism across multiple formats

- Created `StellaOps.TestKit.Tests` project for unit tests related to determinism.
- Implemented `DeterminismManifestTests` to validate deterministic output for canonical bytes and strings, file read/write operations, and error handling for invalid schema versions.
- Added `SbomDeterminismTests` to ensure identical inputs produce consistent SBOMs across SPDX 3.0.1 and CycloneDX 1.6/1.7 formats, including parallel execution tests.
- Updated project references in `StellaOps.Integration.Determinism` to include the new determinism testing library.

docs/marketing/decision-capsules.md

@@ -167,4 +167,4 @@ Decision Capsules connect all four capabilities:
 - `docs/key-features.md` — Feature overview
 - `docs/03_VISION.md` — Product vision and moats
 - `docs/reachability/lattice.md` — Reachability scoring
-- `docs/vex/consensus-overview.md` — VEX consensus engine
+- `docs/16_VEX_CONSENSUS_GUIDE.md` — VEX consensus and issuer trust

docs/marketing/evidence-linked-vex.md

@@ -222,7 +222,7 @@ Evidence-Linked VEX connects to the four capabilities:
 
 ## Related Documentation
 
-- `docs/vex/consensus-overview.md` — VEX consensus engine
+- `docs/16_VEX_CONSENSUS_GUIDE.md` — VEX consensus and issuer trust
 - `docs/reachability/lattice.md` — Reachability scoring model
 - `docs/marketing/decision-capsules.md` — Decision Capsules overview
 - `docs/marketing/hybrid-reachability.md` — Hybrid analysis