feat: add PolicyPackSelectorComponent with tests and integration

- Implemented PolicyPackSelectorComponent for selecting policy packs.
- Added unit tests for component behavior, including API success and error handling.
- Introduced monaco-workers type declarations for editor workers.
- Created acceptance tests for guardrails with stubs for AT1–AT10.
- Established SCA Failure Catalogue Fixtures for regression testing.
- Developed plugin determinism harness with stubs for PL1–PL10.
- Added scripts for evidence upload and verification processes.

src/Web/StellaOps.Web/TASKS.md

@@ -11,3 +11,14 @@
 | WEB-VULN-29-LEDGER-DOC | DONE (2025-12-01) | Findings Ledger proxy contract doc v1.0 with idempotency + retries (`docs/api/gateway/findings-ledger-proxy.md`). |
 | WEB-RISK-68-NOTIFY-DOC | DONE (2025-12-01) | Notifications severity transition event schema v1.0 published (`docs/api/gateway/notifications-severity.md`). |
 | UI-MICRO-GAPS-0209-011 | DOING (2025-12-04) | Motion token catalog + Storybook/Playwright a11y harness added; remaining work: component mapping, perf budgets, deterministic snapshots. |
+| UI-POLICY-20-001 | DONE (2025-12-05) | Policy Studio Monaco editor with DSL highlighting, lint markers, and compliance checklist shipped. |
+| UI-POLICY-20-002 | DONE (2025-12-05) | Simulation panel with deterministic diff rendering shipped (`/policy-studio/packs/:packId/simulate`). |
+| UI-POLICY-20-003 | DONE (2025-12-05) | Approvals workflow UI delivered with submit/review actions, two-person badge, and deterministic log. |
+| UI-POLICY-20-004 | DONE (2025-12-05) | Policy run dashboards delivered with filters, exports, heatmap, and daily deltas. |
+| UI-POLICY-23-000 | DONE (2025-12-05) | Added Policy Studio nav dropdown with pack selector and persisted selection. |
+| UI-POLICY-23-001 | DONE (2025-12-05) | Workspace route `/policy-studio/packs` with pack list + quick actions; cached pack store with offline fallback. |
+| UI-POLICY-23-002 | DONE (2025-12-05) | YAML editor route `/policy-studio/packs/:packId/yaml` with canonical preview and lint diagnostics. |
+| UI-POLICY-23-003 | DONE (2025-12-05) | Rule Builder route `/policy-studio/packs/:packId/rules` with guided inputs and deterministic preview JSON. |
+| UI-POLICY-23-005 | DONE (2025-12-05) | Simulator updated with SBOM/advisory pickers and explain trace view; uses PolicyApiService simulate. |
+| UI-POLICY-23-006 | DOING (2025-12-05) | Explain view route `/policy-studio/packs/:packId/explain/:runId` with trace + JSON export; PDF export pending backend. |
+| UI-POLICY-23-001 | DONE (2025-12-05) | Workspace route `/policy-studio/packs` with pack list + quick actions; cached pack store with offline fallback. |