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.

docs2/testing/router-chaos.md

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+# Router chaos testing
+
+Purpose
+- Validate backpressure, recovery, and cache failure behavior for the router.
+
+Test categories
+- Load testing with spike scenarios (baseline, 10x, 50x, recovery).
+- Backpressure verification for 429 and 503 with Retry-After.
+- Recovery tests to ensure queues drain quickly.
+- Valkey failure injection with graceful fallback.
+
+Expected behavior
+- Normal load returns 200 OK.
+- High load returns 429 with Retry-After.
+- Critical load returns 503 with Retry-After.
+- Recovery within 30 seconds, zero data loss.
+
+Metrics
+- http_requests_total{status}
+- router_request_queue_depth
+- request_recovery_seconds
+
+Alert cues
+- Throttle rate above 10% for 5 minutes.
+- P95 recovery time above 30 seconds.
+- Missing Retry-After headers.
+
+CI integration
+- Runs on PRs touching router code and nightly staging runs.
+- Stores results as artifacts for audits.
+
+Related references
+- operations/router-rate-limiting.md
+- docs/operations/router-chaos-testing-runbook.md