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-scheduler-policy-doc-refresh.md

@@ -0,0 +1,21 @@
+# 2025-10-29 — Scheduler/Policy Guild Doc Refresh
+
+## Summary
+- Extended `SCHED-MODELS-20-001` with environment metadata guidance, lifecycle semantics, and diff payload breakdown for Policy Engine runs.
+- Confirmed `StellaOps.Scheduler.Models.Tests` to keep sample fixtures in sync with the documentation.
+- Ready for distribution to Scheduler (Models/Worker/WebService) and Policy Engine guilds; link this update when posting to internal channels.
+
+## Suggested announcement
+> **Channel(s):** `#scheduler-guild`, `#policy-engine`  
+> **Message:**  
+> ```
+> Policy Engine run DTO docs just picked up a refresh (environment metadata, lifecycle+retry table, diff payload notes).  
+> • Doc: src/Scheduler/__Libraries/StellaOps.Scheduler.Models/docs/SCHED-MODELS-20-001-POLICY-RUNS.md  
+> • Samples: samples/api/scheduler/policy-*.json  
+> • Tests: dotnet test src/Scheduler/__Tests/StellaOps.Scheduler.Models.Tests  
+> Please review for orchestration + API consumer work; ping back if other fields need coverage.  
+> ```
+
+## Follow-up
+- [ ] Confirm both guilds acknowledge the documentation update.
+- [ ] Fold any feedback into Sprint 21 scheduler schema backlog if additional DTO changes are requested.