feat: Add DigestUpsertRequest and LockEntity models

- Introduced DigestUpsertRequest for handling digest upsert requests with properties like ChannelId, Recipient, DigestKey, Events, and CollectUntil.
- Created LockEntity to represent a lightweight distributed lock entry with properties such as Id, TenantId, Resource, Owner, ExpiresAt, and CreatedAt.

feat: Implement ILockRepository interface and LockRepository class

- Defined ILockRepository interface with methods for acquiring and releasing locks.
- Implemented LockRepository class with methods to try acquiring a lock and releasing it, using SQL for upsert operations.

feat: Add SurfaceManifestPointer record for manifest pointers

- Introduced SurfaceManifestPointer to represent a minimal pointer to a Surface.FS manifest associated with an image digest.

feat: Create PolicySimulationInputLock and related validation logic

- Added PolicySimulationInputLock record to describe policy simulation inputs and expected digests.
- Implemented validation logic for policy simulation inputs, including checks for digest drift and shadow mode requirements.

test: Add unit tests for ReplayVerificationService and ReplayVerifier

- Created ReplayVerificationServiceTests to validate the behavior of the ReplayVerificationService under various scenarios.
- Developed ReplayVerifierTests to ensure the correctness of the ReplayVerifier logic.

test: Implement PolicySimulationInputLockValidatorTests

- Added tests for PolicySimulationInputLockValidator to verify the validation logic against expected inputs and conditions.

chore: Add cosign key example and signing scripts

- Included a placeholder cosign key example for development purposes.
- Added a script for signing Signals artifacts using cosign with support for both v2 and v3.

chore: Create script for uploading evidence to the evidence locker

- Developed a script to upload evidence to the evidence locker, ensuring required environment variables are set.

tools/zastava-upload-evidence.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ -z "${EVIDENCE_LOCKER_URL:-}" || -z "${CI_EVIDENCE_LOCKER_TOKEN:-}" ]]; then
+  echo "EVIDENCE_LOCKER_URL and CI_EVIDENCE_LOCKER_TOKEN are required" >&2
+  exit 1
+fi
+
+STAGED_DIR="evidence-locker/zastava/2025-12-02"
+TAR_OUT="/tmp/zastava-evidence.tar"
+
+test -d "$STAGED_DIR" || { echo "missing staged dir $STAGED_DIR" >&2; exit 1; }
+
+tar -cf "$TAR_OUT" -C "$STAGED_DIR" .
+
+curl --retry 3 --retry-delay 2 --fail \
+  -H "Authorization: Bearer $CI_EVIDENCE_LOCKER_TOKEN" \
+  -X PUT "$EVIDENCE_LOCKER_URL/zastava/2025-12-02/zastava-evidence.tar" \
+  --data-binary "@$TAR_OUT"
+
+echo "Uploaded $TAR_OUT to $EVIDENCE_LOCKER_URL/zastava/2025-12-02/"