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.

tools/signals-verify-evidence-tar.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+TAR_PATH=${1:-evidence-locker/signals/2025-12-05/signals-evidence.tar}
+EXPECTED_SHA=${EXPECTED_SHA:-a17910b8e90aaf44d4546057db22cdc791105dd41feb14f0c9b7c8bac5392e0d}
+
+if [[ ! -f "$TAR_PATH" ]]; then
+  echo "missing tar: $TAR_PATH" >&2
+  exit 1
+fi
+
+sha=$(sha256sum "$TAR_PATH" | awk '{print $1}')
+if [[ -n "$EXPECTED_SHA" && "$sha" != "$EXPECTED_SHA" ]]; then
+  echo "sha mismatch: got $sha expected $EXPECTED_SHA" >&2
+  exit 2
+fi
+
+tmpdir=$(mktemp -d)
+trap 'rm -rf "$tmpdir"' EXIT
+
+tar -xf "$TAR_PATH" -C "$tmpdir"
+(cd "$tmpdir/evidence-locker/signals/2025-12-05" && sha256sum --check SHA256SUMS)
+
+echo "OK: tar hash=${sha} (expected=${EXPECTED_SHA:-<not set>}); inner SHA256SUMS verified"