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/cli/README.md

@@ -0,0 +1,40 @@
+# StellaOps CLI
+
+The `stella` CLI is the operator-facing Swiss army knife for scans, exports, policy management, offline kit operations, and automation scripting.
+
+## Responsibilities
+- Deliver deterministic verbs for scan, diff, export, policy, and observability operations.
+- Handle interactive and non-interactive authentication via Authority (device code, client credentials).
+- Support offline kit workflows including bundle verification and seed installation.
+- Expose JSON outputs suitable for CI parity and golden tests.
+
+## Key components
+- `StellaOps.Cli` native AOT host.
+- Shared helpers in `StellaOps.Cli.Core`.
+- Restart-time plug-ins under `StellaOps.Cli.Plugins.*`.
+
+## Integrations & dependencies
+- Authority for token exchange.
+- Backend APIs (Scanner, Policy, Export Center, Notify).
+- Offline kit bundles and local keychain/DPoP storage.
+
+## Operational notes
+- Deterministic output fixtures under `src/Cli/StellaOps.Cli.Tests`.
+- Versioned command docs in `docs/modules/cli/guides`.
+- Plugin catalogue in `plugins/cli/**` (restart-only).
+
+## Related resources
+- ./guides/20_REFERENCE.md
+- ./guides/cli-reference.md
+- ./guides/policy.md
+
+## Backlog references
+- DOCS-CLI-OBS-52-001 / DOCS-CLI-FORENSICS-53-001 in ../../TASKS.md.
+- CLI-CORE-41-001 epic in `src/Cli/StellaOps.Cli/TASKS.md`.
+
+## Epic alignment
+- **Epic 2 – Policy Engine & Editor:** deliver deterministic policy authoring, simulation, and explain verbs.
+- **Epic 4 – Policy Studio:** integrate registry/promotion workflows, approvals, and lint tooling.
+- **Epic 6 – Vulnerability Explorer:** surface triage and ledger operations.
+- **Epic 10 – Export Center:** orchestrate export requests, verification, and Offline Kit automation.
+- **Epic 11 – Notifications Studio:** manage notification authoring/previews from the command line.