feat(policy): persist gate evaluation queue, snapshots, orchestrator jobs

Policy Engine: moves gate evaluation, snapshots, orchestrator job tracking,
and ledger export from in-memory state to Postgres-backed stores.

- New persistence migrations 007 (runtime state), 008 (snapshot artifact
  identity), 009 (orchestrator jobs).
- New repositories: PolicyEngineSnapshotRepository,
  PolicyEngineLedgerExportRepository, PolicyEngineOrchestratorJobRepository,
  WorkerResultRepository.
- Gateway services: GateEvaluationJobDispatchService,
  GateEvaluationJobStatusService, GateEvaluationJobWorker,
  SchedulerBackedGateEvaluationQueue (plus Unsupported fallback),
  GateTargetSnapshotMaterializer, PersistedKnowledgeSnapshotStore,
  GateBaselineBootstrapper, PolicyGateEvaluationJobExecutor.
- New endpoints: GateJobEndpoints for job status + dispatch.
- Worker host: PolicyOrchestratorJobWorkerHost to drain the persistent queue.
- PersistedOrchestratorStores + DeltaSnapshotServiceAdapter swap in the
  persistent implementations via DI.

Tests: PersistedDeltaRuntimeTests, PolicyEngineGateTargetSnapshotRuntimeTests,
PolicyEngineRegistryWebhookRuntimeTests, PostgresLedgerExportStoreTests,
PostgresSnapshotStoreTests, PolicyGatewayPersistedDeltaRuntimeTests,
RegistryWebhookQueueRuntimeTests. Archives the old S001 demo seed.

Docs: policy API + architecture pages updated.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/api/policy.md

@@ -407,6 +407,58 @@ Scopes: policy:runs, policy:simulate
 
 Produces sealed bundle for determinism verification; returns location of bundle.
 
+### 6.6 Orchestrator Job Producer Runtime
+
+The engine-owned orchestration surface is exposed directly under `/policy/*`. Unlike the stateless batch evaluator below, this path persists orchestrator and worker state in Policy storage.
+
+```
+POST /policy/orchestrator/jobs
+Scopes: policy:run
+```
+
+**Request**
+
+```json
+{
+  "tenantId": "acme",
+  "policyVersion": "sha256:1fb2...",
+  "items": [
+    {
+      "findingId": "acme::artifact-1::CVE-2024-12345",
+      "eventId": "5d1fcc61-6903-42ef-9285-7f4d3d8f7f69",
+      "event": { "...": "canonical ledger payload" }
+    }
+  ]
+}
+```
+
+**Response 200**
+
+```json
+{
+  "jobId": "01HSR2M1D0BP7V2QY3QGJ31Z8V",
+  "status": "queued",
+  "requestedAt": "2026-04-15T08:30:00Z",
+  "completedAt": null,
+  "resultHash": null
+}
+```
+
+Related endpoints:
+
+```
+POST /policy/orchestrator/jobs/preview
+GET /policy/orchestrator/jobs/{jobId}
+GET /policy/worker/jobs/{jobId}
+```
+
+Runtime contract:
+
+- Submitting `/policy/orchestrator/jobs` now signals the engine background worker, which leases queued jobs, marks them `running`, executes `PolicyWorkerService`, persists `policy.worker_results`, and records terminal `completed` or `failed` state on the orchestrator job.
+- Clients should poll `GET /policy/orchestrator/jobs/{jobId}` for status and read the final materialized worker payload from `GET /policy/worker/jobs/{jobId}`.
+- `POST /policy/orchestrator/jobs/preview` remains non-mutating.
+- `POST /api/policy/eval/batch` remains explicitly stateless and must not be used as a persistence side channel for orchestrator or worker rows.
+
 ---
 
 ## 7 · Batch Evaluation API