Add unit tests for PackRunAttestation and SealedInstallEnforcer

- Implement comprehensive tests for PackRunAttestationService, covering attestation generation, verification, and event emission.
- Add tests for SealedInstallEnforcer to validate sealed install requirements and enforcement logic.
- Introduce a MonacoLoaderService stub for testing purposes to prevent Monaco workers/styles from loading during Karma runs.

src/Web/StellaOps.Web/angular.json

@@ -91,6 +91,12 @@
             "tsConfig": "tsconfig.spec.json",
             "karmaConfig": "karma.conf.cjs",
             "inlineStyleLanguage": "scss",
+            "fileReplacements": [
+              {
+                "replace": "src/app/features/policy-studio/editor/monaco-loader.service.ts",
+                "with": "src/app/features/policy-studio/editor/monaco-loader.service.stub.ts"
+              }
+            ],
             "assets": [
               "src/favicon.ico",
               "src/assets",