Correct Ghost Radio's sitemap namespace for Search Console

Context

On 2026-08-13, Google Search Console auto-verified https://ghost.radio.fm/ via the deployed HTML verification file and accepted sitemap.xml. After processing, Search Console reported that the sitemap was readable and discovered both canonical URLs, but returned one error: Incorrect namespace at line 2 on the urlset tag.

The production sitemap declares http://www.sitemaps.org/protocol/sitemap/0.9; the sitemap protocol requires http://www.sitemaps.org/schemas/sitemap/0.9. Existing issue #46 completed the Netlify production-host and discovery-file deployment, and its agent instructions require newly evidenced code defects to be split into a scoped issue.

The homepage is already indexed. /classic was Discovered - currently not indexed; an indexing request was accepted and added it to Google's priority crawl queue.

Acceptance Criteria

• examples/playground/public/sitemap.xml declares http://www.sitemaps.org/schemas/sitemap/0.9 on the urlset element.
• A regression test fails for the non-standard protocol namespace and passes for the standard schemas namespace.
• The sitemap retains exactly the two canonical URLs https://ghost.radio.fm/ and https://ghost.radio.fm/classic.
• The full unit suite, typecheck, package build, and SEO checker pass.
• After a separately approved merge and production deployment, the live sitemap serves the corrected namespace and Search Console no longer reports the namespace error after reprocessing.

Tests/Evals

• Add a focused assertion to test/seoCheck.test.ts for the exact standard namespace.
• Preserve the existing sitemap URL-order check in scripts/check-seo.mjs.
• Re-run Google Search Console sitemap processing only after production serves the corrected XML.

Verification

• pnpm exec vitest run test/seoCheck.test.ts
• pnpm test:run
• pnpm typecheck
• pnpm build
• pnpm check:seo
• git diff --check

Agent Instructions

• Keep the code change to the sitemap namespace and its regression test.
• Preserve player behavior, tracks, audio, package exports, skins, routes, metadata, and committed dist/.
• Commit and push the verified branch, then open a draft PR.
• Do not merge, deploy, resubmit the sitemap, or request indexing without explicit human approval and live production evidence.

Out of Scope

• Changes to sitemap membership, canonical URLs, robots directives, page metadata, player code, packages, hosting, DNS, analytics, or unrelated Search Console properties.
• Reopening the completed production-host issue Choose the production host and publish Ghost Radio discovery files #46.

Linear

• None. GitHub issue Choose the production host and publish Ghost Radio discovery files #46 and the authenticated Search Console receipt are the source trail.