feat(docs): Add comprehensive documentation for Vexer, Vulnerability Explorer, and Zastava modules

- Introduced AGENTS.md, README.md, TASKS.md, and implementation_plan.md for Vexer, detailing mission, responsibilities, key components, and operational notes.
- Established similar documentation structure for Vulnerability Explorer and Zastava modules, including their respective workflows, integrations, and observability notes.
- Created risk scoring profiles documentation outlining the core workflow, factor model, governance, and deliverables.
- Ensured all modules adhere to the Aggregation-Only Contract and maintain determinism and provenance in outputs.

docs/modules/concelier/README.md

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+# StellaOps Concelier
+
+Concelier ingests signed advisories from dozens of sources and converts them into immutable observations plus linksets under the Aggregation-Only Contract (AOC).
+
+## Responsibilities
+- Fetch and normalise vulnerability advisories via restart-time connectors.
+- Persist observations and correlation linksets without precedence decisions.
+- Emit deterministic exports (JSON, Trivy DB) for downstream policy evaluation.
+- Coordinate offline/air-gap updates via Offline Kit bundles.
+
+## Key components
+- `StellaOps.Concelier.WebService` orchestration host.
+- Connector libraries under `StellaOps.Concelier.Connector.*`.
+- Exporter packages (`StellaOps.Concelier.Exporter.*`).
+
+## Integrations & dependencies
+- MongoDB for canonical observations and schedules.
+- Policy Engine / Export Center / CLI for evidence consumption.
+- Notify and UI for advisory deltas.
+
+## Operational notes
+- Connector runbooks in ./operations/connectors/.
+- Mirror operations for Offline Kit parity.
+- Grafana dashboards for connector health.
+
+## Related resources
+- ./operations/conflict-resolution.md
+- ./operations/mirror.md
+
+## Backlog references
+- DOCS-LNM-22-001, DOCS-LNM-22-007 in ../../TASKS.md.
+- Connector-specific TODOs in `src/Concelier/**/TASKS.md`.
+
+## Epic alignment
+- **Epic 1 – AOC enforcement:** uphold raw observation invariants, provenance requirements, linkset-only enrichment, and AOC verifier guardrails across every connector.
+- **Epic 10 – Export Center:** expose deterministic advisory exports and metadata required by JSON/Trivy/mirror bundles.