Fix public landing canonicals

[sarthakagrawal927]

Summary

• emit self-referencing canonical and Open Graph URLs for every sitemap page
• verify all sitemap URLs against built HTML during every build
• correct the deployment smoke-check hostname
• correct the root structured-data identity discovered during the same audit
• patch the newly disclosed nanoid advisory in the existing development-tool override

Validation

• pnpm build
• pnpm check:docs
• pnpm quality:dependencies
• git diff --check

Closes #37
Closes #38
Closes #40