Migrate a WordPress site to headless with a Next.js frontend

Our editorial team is happy in WordPress but our Core Web Vitals are poor and the theme is unmaintainable. The job: • Keep WordPress as a headless CMS via the REST API or WPGraphQL • Rebuild the frontend in Next.js with incremental static regeneration • Preserve every existing URL — we have 800+ indexed posts and cannot afford to lose them, so a redirect map is part of the deliverable • Carry over Yoast metadata into the new head tags • Target LCP under 2.5s on a mid-range Android over 3G Please be specific in your proposal about how you would handle the redirect map and preview mode for editors.