refactor(ci): rename the approval workflow to match its tooling

The workflow file was the only name in the set still saying "core":
the job, the helper script, and the check context all say maintainer
approval. Nothing references the file by name, and the required check
context is the job name rather than the file, so this is a pure rename.

Signed-off-by: Jim Meyer <jimeyer@nvidia.com>

Author: purp

.github/workflows/maintainer-approval.yml

@@ -0,0 +1,73 @@
+# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+name: Maintainer Approval
+
+on:
+  merge_group:
+    types: [checks_requested]
+  pull_request_review:
+    types: [submitted, dismissed]
+
+permissions:
+  contents: read
+  pull-requests: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  maintainer-approval:
+    # This name is the required status check context. Changing it silently
+    # breaks the ruleset entry that gates merges on this job.
+    name: OpenShell / Maintainer Approval
+    if: github.repository_owner == 'NVIDIA'
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      # Check out the default branch, never the pull request head. Both the
+      # maintainer list and the decision helper must come from main: reading
+      # either from the pull request ref would let a contributor add themselves
+      # to the list, or rewrite the decision logic, and self-approve.
+      - name: Check out the maintainer list and helper
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          ref: main
+          sparse-checkout: |
+            MAINTAINERS.md
+            tasks/scripts/check_maintainer_approval.py
+          sparse-checkout-cone-mode: false
+          persist-credentials: false
+
+      - name: Require an approving review from a maintainer
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          # merge_group carries no pull request in its payload, but the queue
+          # branch names the entry: gh-readonly-queue/main/pr-3027-<base sha>.
+          MERGE_GROUP_REF: ${{ github.ref_name }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          if [ -z "${PR_NUMBER:-}" ]; then
+            if [[ "$MERGE_GROUP_REF" =~ /pr-([0-9]+)-[0-9a-f]+$ ]]; then
+              PR_NUMBER="${BASH_REMATCH[1]}"
+            else
+              # Fail closed: an unrecognised ref must never satisfy the gate.
+              echo "::error::No pull request resolved from '$MERGE_GROUP_REF'."
+              exit 1
+            fi
+          fi
+
+          gh api --paginate "repos/$GH_REPO/pulls/$PR_NUMBER/reviews" --jq '.[]' \
+            | jq -s '.' > reviews.json
+
+          # Exits non-zero when no maintainer's latest decisive review is an
+          # approval, and when MAINTAINERS.md yields no handles. That exit code
+          # is the check result; nothing is posted anywhere.
+          python3 tasks/scripts/check_maintainer_approval.py \
+            --maintainers MAINTAINERS.md \
+            --reviews reviews.json