chore: import upstream snapshot with attribution

.github/workflows/github-autoclose.yml

@@ -0,0 +1,71 @@
+name: GitHub - Autoclose Invalid PRs
+on:
+  pull_request_target:
+    branches:
+      - 'main'
+    paths:
+      - '.gitignore'
+
+jobs:
+  autoclose:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            const files = await github.rest.pulls.listFiles({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              pull_number: context.payload.pull_request.number,
+            });
+            if (
+              files.data.length !== 1 ||
+              (files.data[0].filename !== ".gitignore" &&
+              // We've had four PRs make this same (irrelevant) change already.
+                !(files.data[0].filename === "664ef4623946e65e18d59764.md" &&
+                  files.data[0].patch.includes("return re.sub('(?<!\d)1', '', equation_string.strip('+'))")
+                )
+              )
+            ) {
+              return;
+            }
+            const creator = context.payload.sender.login;
+            const opts = github.rest.issues.listForRepo.endpoint.merge({
+              ...context.issue,
+              creator,
+              state: 'all'
+            });
+            const issues = await github.paginate(opts);
+
+            // iterate through issues
+            for (const issue of issues) {
+              // if the issue is this one, keep looking
+              if (issue.number === context.issue.number) {
+                continue;
+              }
+
+              // if the issue is actually a PR, they're not a first timer
+              if (issue.pull_request) {
+                return // Creator is already a contributor.
+              }
+            }
+            core.setFailed("Invalid PR detected.");
+            await github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: "Thank you for opening this pull request.\n\nThis is a standard message notifying you that we've reviewed your pull request and have decided not to merge it. We would welcome future pull requests from you.\n\nThank you and happy coding.",
+            });
+            await github.rest.pulls.update({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              pull_number: context.payload.pull_request.number,
+              state: "closed"
+            });
+            await github.rest.issues.addLabels({
+              owner: context.payload.repository.owner.login,
+              repo: context.payload.repository.name,
+              issue_number: context.issue.number,
+              labels: ["spam"]
+            });