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/2025-10-29-export-center-provenance.md

@@ -0,0 +1,9 @@
+# 2025-10-29 – Export Center provenance/signing doc
+
+## Summary
+- Authored `docs/modules/export-center/provenance-and-signing.md`, covering manifest/provenance artefacts, cosign/SLSA signing pipeline, verification workflows (CLI/CI/offline), and compliance checklist.
+- Cross-linked the new guide from the docs index (`docs/README.md`) and referenced outstanding CLI automation (`CLI-EXPORT-37-001`) to keep verification guidance aligned with upcoming tooling.
+
+## Follow-ups
+- [ ] Revisit once `CLI-EXPORT-37-001` lands to confirm command names/flags and update the verification section if necessary.
+- [ ] Sync with DevOps (`DEVOPS-EXPORT-37-001`) after dashboards/alerts ship to embed direct links in the failure handling section.