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.

scripts/packs/__fixtures__/good/files.txt

@@ -0,0 +1,10 @@
+canonical-plan.json
+inputs.lock
+sbom.json
+attestation.dsse
+approvals-ledger.dsse
+revocations.json
+bundle.dsse
+attestation.dsse.sig
+redaction-policy.json
+packs/demo-pack.tgz