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.

tests/plugins/plugin-index.json

@@ -0,0 +1,12 @@
+{
+  "version": "0.1.0-stub",
+  "plugins": [
+    {
+      "id": "example-plugin",
+      "capabilities": ["scan", "report"],
+      "dsse_manifest": "manifests/example-plugin.dsse",
+      "resource_limits": {"cpu": "500m", "memory": "256Mi"},
+      "revocation": {"cve_list": ["CVE-2025-0001"], "status": "active"}
+    }
+  ]
+}