feat: Add comprehensive product advisories for improved scanner functionality

- Introduced a blueprint for explainable quiet alerts, detailing phases for SBOM, VEX readiness, and attestations.
- Developed a roadmap for deterministic diff-aware rescans, enhancing scanner speed and efficiency.
- Implemented a hash-based SBOM layer cache to optimize container scans by reusing previous results.
- Created a multi-runtime reachability corpus to validate function-level reachability across various programming languages.
- Proposed a stable SBOM model using SPDX 3.0.1 for persistence and CycloneDX 1.6 for interchange.
- Established a validation plan for quiet scans, focusing on provenance and CI integration.
- Documented guidelines for the Findings Ledger module, outlining roles, execution rules, and testing protocols.

docs/implplan/archived/updates/2025-10-30-devops-governance.md

@@ -0,0 +1,17 @@
+# 30 Oct 2025 — Governance rules anchor consolidated
+
+**What changed**
+
+- Published `docs/devops/contracts-and-rules.md` capturing the Sprint 33 governance rules:
+  1. API Gateway remains a proxy; Policy Engine composes overlays/simulations.
+  2. AOC ingestion persists upstream truth only (no merge/deduplicate logic).
+  3. Graph platform standardised on Graph Indexer + Graph API (Cartographer retired).
+- Updated backlog hygiene note (`docs/backlog/2025-10-cleanup.md`) and archived the Cartographer handshake plan to point at the new graph platform.
+- Logged the rules in `ops/devops/TASKS.md` and corresponding sprint file `docs/implplan/SPRINT_*.md`, removing duplicate references to Cartographer as an active service.
+
+**Reviewers / acknowledgements**
+
+- Platform Leads (DevOps + Graph) confirmed the retirement of Cartographer in favour of Graph Indexer + Graph API.
+- Policy Engine Guild acknowledged the proxy-only Gateway posture and downstream overlay ownership.
+
+See `DEVOPS-RULES-33-001` for the owning task.