Fix SEO remediation gaps - #5

Summary

• Scope sitemap lastmod generation to page-level and tool-manifest inputs to avoid release-wide date churn
• Move tool handoff payloads from query strings to hash fragments while keeping legacy query parsing compatible
• Add deployment-level 301 redirects for legacy cron alias routes and remove the inline redirect script fallback
• Allowlist FAQPage structured data to high-confidence tool pages and keep the FAQ schema gate in post-build checks
• Align root x-default sitemap targets and add SEO regression guardrails

Verification

• npm run lint
• npm test
• npm run validate
• npm run build:app
• npm run build:post
• npm run test:e2e:smoke