feat: Add VEX compact fixture and implement offline verifier for Findings Ledger exports

- Introduced a new VEX compact fixture for testing purposes.
- Implemented `verify_export.py` script to validate Findings Ledger exports, ensuring deterministic ordering and applying redaction manifests.
- Added a lightweight stub `HarnessRunner` for unit tests to validate ledger hashing expectations.
- Documented tasks related to the Mirror Creator.
- Created models for entropy signals and implemented the `EntropyPenaltyCalculator` to compute penalties based on scanner outputs.
- Developed unit tests for `EntropyPenaltyCalculator` to ensure correct penalty calculations and handling of edge cases.
- Added tests for symbol ID normalization in the reachability scanner.
- Enhanced console status service with comprehensive unit tests for connection handling and error recovery.
- Included Cosign tool version 2.6.0 with checksums for various platforms.

docs/modules/mirror/signing-runbook.md

@@ -12,6 +12,8 @@
     MIRROR_SIGN_KEY_B64: ${{ secrets.MIRROR_SIGN_KEY_B64 }}
     REQUIRE_PROD_SIGNING: 1
     OCI: 1
+    TENANT_SCOPE: tenant-demo
+    ENV_SCOPE: lab
   run: |
     scripts/mirror/check_signing_prereqs.sh
     scripts/mirror/ci-sign.sh
@@ -40,7 +42,9 @@ MIRROR_SIGN_KEY_B64=LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCk1DNENBUUF3QlFZREsyVndC
 **Do not ship with this key.** Set `REQUIRE_PROD_SIGNING=1` for release/tag builds so they fail without the real key. Add the production key as a Gitea secret (`MIRROR_SIGN_KEY_B64`) and rerun the workflow; remove this temporary key block once rotated.
 
 ## Verification
-The CI step already runs `scripts/mirror/verify_thin_bundle.py`. For OCI, ensure `out/mirror/thin/oci/index.json` references the manifest digest.
+The CI step already runs `scripts/mirror/verify_thin_bundle.py --bundle-meta mirror-thin-v1.bundle.json --tenant $TENANT_SCOPE --environment $ENV_SCOPE --pubkey out/mirror/thin/tuf/keys/ci-ed25519.pub` so offline-kit policies (OK1–OK10), Rekor policy (RK1–RK10), and mirror-format policy (MS1–MS10) are validated alongside the tarball. For OCI, ensure `out/mirror/thin/oci/index.json` references the manifest digest.
+
+`milestone.json` now carries manifest/tar/bundle/bundle-dsse hashes plus policy layer hashes to allow air-gapped import verification.
 
 ## Fallback (if secret absent)
 - CI can fall back to an embedded test Ed25519 key when `MIRROR_SIGN_KEY_B64` is unset **only when `REQUIRE_PROD_SIGNING` is not set**. This is for dev smoke runs; release/tag jobs must set `REQUIRE_PROD_SIGNING=1` to forbid fallback.