chore: import upstream snapshot with attribution

.github/scripts/pr-guidelines/check-pr-template.js

@@ -0,0 +1,39 @@
+'use strict';
+
+module.exports = async ({ github, context, core, isAllowListed }) => {
+  if (isAllowListed === 'true') return;
+
+  const body = (context.payload.pull_request.body || '').toLowerCase();
+
+  // The template must be present and the first 3 checkboxes must be
+  // ticked. The last checkbox (tested locally) is acceptable to leave
+  // unticked.
+  const templatePresent = body.includes('checklist:');
+  const requiredTicked = [
+    'i have read and followed the contribution guidelines',
+    'i have read and followed the how to open a pull request guide',
+    'my pull request targets the'
+  ];
+  // Strip markdown links ([text](url) → text) before matching so contributors
+  // who omit the link syntax (e.g. type plain text) still pass the check.
+  const normalizedBody = body
+    .replace(/\[\s*x\s*\]/g, '[x]')
+    .replace(/\[([^\]]+)\]\([^)]+\)/g, '$1');
+  const allRequiredTicked = requiredTicked.every(item =>
+    normalizedBody.includes(`[x] ${item}`)
+  );
+
+  if (templatePresent && allRequiredTicked) return;
+
+  core.setOutput('failure_reason', 'incomplete_checklist');
+  core.setFailed(
+    'PR description is missing the required checklist or some items are incomplete.'
+  );
+
+  await github.rest.issues.addLabels({
+    owner: context.repo.owner,
+    repo: context.repo.repo,
+    issue_number: context.payload.pull_request.number,
+    labels: ['deprioritized']
+  });
+};