feat(action-lint)!: drop runner-labels input; consumers commit .github/actionlint.yaml directly per actionlint convention

Author: bwlkr

.github/workflows/action-lint.yaml

@@ -6,8 +6,10 @@ on:
       runs-on:
         description: >-
           Runner label. Defaults to ubuntu-latest. Override to a self-hosted
-          runner label if you want to run CI on your own scale set; pair with
-          runner-labels so actionlint accepts the label.
+          runner label if you want to run CI on your own scale set. To
+          register custom self-hosted runner labels with actionlint, commit
+          a .github/actionlint.yaml file in the calling repo — see
+          https://github.com/rhysd/actionlint/blob/main/docs/config.md.
         required: false
         default: ubuntu-latest
         type: string
@@ -21,18 +23,6 @@ on:
         required: false
         default: v1.7.12
         type: string
-      runner-labels:
-        description: >-
-          Comma- or newline-separated list of self-hosted runner label names
-          (e.g. "fast-runner,gpu-runner"). When set, the workflow writes a
-          temporary .github/actionlint.yaml registering these labels so
-          actionlint doesn't flag `runs-on: <label>` as unknown. Ignored if
-          the calling repo already commits a .github/actionlint.yaml. Leave
-          empty (default) if you only use GitHub-hosted runners or ship your
-          own actionlint config.
-        required: false
-        default: ""
-        type: string
 
 permissions:
   contents: read
@@ -57,31 +47,6 @@ jobs:
           GOBIN="$RUNNER_TEMP/bin" go install github.com/rhysd/actionlint/cmd/actionlint@${{ inputs.actionlint-version }}
           echo "$RUNNER_TEMP/bin" >> "$GITHUB_PATH"
 
-      # Register self-hosted runner labels with actionlint when the caller
-      # passes them as input. Skipped if the calling repo already ships its
-      # own .github/actionlint.yaml — that takes precedence.
-      - name: Register runner labels
-        if: inputs.runner-labels != ''
-        shell: bash
-        env:
-          LABELS: ${{ inputs.runner-labels }}
-        run: |
-          if [ -f .github/actionlint.yaml ] || [ -f .github/actionlint.yml ]; then
-            echo "Calling repo provides its own .github/actionlint.yaml — leaving untouched"
-            exit 0
-          fi
-          mkdir -p .github
-          {
-            echo "self-hosted-runner:"
-            echo "  labels:"
-            echo "${LABELS}" | tr ',' '\n' | while IFS= read -r label; do
-              label="$(echo "${label}" | tr -d '[:space:]')"
-              [ -n "${label}" ] && echo "    - ${label}"
-            done
-          } > .github/actionlint.yaml
-          echo "Wrote .github/actionlint.yaml from runner-labels input:"
-          cat .github/actionlint.yaml
-
       - name: Run actionlint
         id: actionlint
         run: actionlint