[CI] (.github/workflows, scripts, scripts/data): check commit messages, comment text and formatting

.github/workflows/hygiene.yml

@@ -0,0 +1,34 @@
+name: Text hygiene
+
+# CONTRIBUTING.md's checks: the pushed commits' messages, the source-text rules and ratchets, and
+# clang-format on each commit's changed lines. This is its own workflow without a concurrency
+# group, so a later push never cancels it and every push's commits are checked.
+on:
+  push:
+    branches: ['**']
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  text-hygiene:
+    name: Commit messages and source text
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+    env:
+      TEXT_HYGIENE_BASE_BRANCH: feat/disaggregated
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+      - name: Install clang-format
+        run: |
+          python3 -m venv "${RUNNER_TEMP}/clang-format"
+          "${RUNNER_TEMP}/clang-format/bin/pip" install --quiet 'clang-format==23.1.3'
+          echo "CLANG_FORMAT=${RUNNER_TEMP}/clang-format/bin/clang-format" >> "${GITHUB_ENV}"
+      - name: Lint self-test
+        run: python3 scripts/check_text_hygiene.py self-test
+      - name: Check commits, source text and formatting
+        run: python3 scripts/check_text_hygiene.py ci