ci: rebuild backend golden image on lockfile changes

.gitea/workflows/ci-cd.yml

@@ -104,9 +104,16 @@ jobs:
           fi
           docker buildx inspect --bootstrap
 
+          lockfile_sha="$(sha256sum uv.lock | awk '{ print $1 }')"
+
           image_usable() {
             docker run --rm "${CI_GOLDEN_REF}:${GOLDEN_TAG}" \
-              bash -c '/app/.venv/bin/ruff --version >/dev/null && /app/.venv/bin/python -m pytest --version >/dev/null'
+              bash -c "
+                test -f /app/uv.lock
+                test \"\$(sha256sum /app/uv.lock | awk '{ print \$1 }')\" = '${lockfile_sha}'
+                /app/.venv/bin/ruff --version >/dev/null
+                /app/.venv/bin/python -m pytest --version >/dev/null
+              "
           }
 
           if ! docker buildx imagetools inspect "${CI_GOLDEN_REF}:${GOLDEN_TAG}" >/dev/null 2>&1 || ! image_usable; then