feat: Implement advisory event replay API with conflict explainers

- Added `/concelier/advisories/{vulnerabilityKey}/replay` endpoint to return conflict summaries and explainers.
- Introduced `MergeConflictExplainerPayload` to structure conflict details including type, reason, and source rankings.
- Enhanced `MergeConflictSummary` to include structured explainer payloads and hashes for persisted conflicts.
- Updated `MirrorEndpointExtensions` to enforce rate limits and cache headers for mirror distribution endpoints.
- Refactored tests to cover new replay endpoint functionality and validate conflict explainers.
- Documented changes in TASKS.md, noting completion of mirror distribution endpoints and updated operational runbook.

docs/ARCHITECTURE_DEVOPS.md

@@ -337,7 +337,7 @@ Prometheus + OTLP; Grafana dashboards ship in the charts.
 * **Vulnerability response**:
 
   * Concelier red-flag advisories trigger accelerated **stable** patch rollout; UI/CLI “security patch available” notice.
-  * 2025-10: Pinned `MongoDB.Driver` **3.5.0** and `SharpCompress` **0.41.0** across services (DEVOPS-SEC-10-301) to eliminate NU1902/NU1903 warnings surfaced during scanner cache/worker test runs; future dependency bumps follow the same central override pattern.
+  * 2025-10: Pinned `MongoDB.Driver` **3.5.0** and `SharpCompress` **0.41.0** across services (DEVOPS-SEC-10-301) to eliminate NU1902/NU1903 warnings surfaced during scanner cache/worker test runs; repacked the local `Mongo2Go` feed so test fixtures inherit the patched dependencies; future bumps follow the same central override pattern.
 
 * **Backups/DR**: