fix: use bash arrays for BUILD_ARGS and LABELS to handle values with spaces

Labels like org.opencontainers.image.description="Python GitHub Runner"
contain spaces. Using unquoted string variables caused word-splitting when
passed to buildah, resulting in "accepts at most 1 arg(s), received 13".

Switch to bash arrays with proper quoting so values with spaces are passed
as single arguments.

https://claude.ai/code/session_01WtJC749bMVKy7Xxr5P2WD7

Author: claude

.github/workflows/release.yaml

@@ -60,33 +60,32 @@ jobs:
           IMAGE_FORMAT: ${{ steps.manifest.outputs.format }}
         run: |
           # Build args from manifest
-          BUILD_ARGS=""
-          for arg in $(yq e '.build.args[]' manifest.yaml); do
-            BUILD_ARGS="${BUILD_ARGS} --build-arg ${arg}"
-          done
+          BUILD_ARGS=()
+          while IFS= read -r arg; do
+            BUILD_ARGS+=(--build-arg "${arg}")
+          done < <(yq e '.build.args[]' manifest.yaml)
 
           # Labels from manifest
-          LABELS=""
+          LABELS=()
           while IFS= read -r label; do
             if [[ -n "${label}" ]]; then
               label_key="${label%%=*}"
               label_value="${label#*=}"
               label_value="${label_value%\"}"
               label_value="${label_value#\"}"
-              LABELS="${LABELS} --label ${label_key}=${label_value}"
+              LABELS+=(--label "${label_key}=${label_value}")
             fi
           done < <(yq e '.build.labels[]' manifest.yaml)
 
           # Add version label
-          LABELS="${LABELS} --label org.opencontainers.image.version=${IMAGE_VERSION}"
+          LABELS+=(--label "org.opencontainers.image.version=${IMAGE_VERSION}")
 
-          # shellcheck disable=SC2086
           buildah build \
             --squash \
             --pull-always \
             --format "${IMAGE_FORMAT}" \
-            ${BUILD_ARGS} \
-            ${LABELS} \
+            "${BUILD_ARGS[@]}" \
+            "${LABELS[@]}" \
             --tag "${IMAGE_NAME}:${IMAGE_VERSION}" \
             .