Publish multi-version documentation site (#1727)

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: bb4b44f0-f505-49c5-9878-76e2b40c7a15
Copilot-Session: 8eac1204-10ae-4319-9333-aee5dd43dcc8

scripts/manifest-path.mjs

@@ -0,0 +1,16 @@
+// Location of the docs-versions manifest.
+//
+// This manifest is a build-time artifact produced during docs publishing, which
+// only ever runs in CI -- never on a developer's machine. It therefore lives in
+// the runner's temporary directory (RUNNER_TEMP on GitHub Actions, falling back
+// to the OS temp dir for local testing) so it never touches the repository tree
+// and needs no .gitignore entry. Every script agrees on this path, so the
+// workflow does not need to thread it between steps.
+
+import os from "node:os";
+import path from "node:path";
+
+export const manifestPath = path.join(
+  process.env.RUNNER_TEMP || os.tmpdir(),
+  "docs-versions.json"
+);