Technical SEO audit: JavaScript rendering and crawlability on a React (Vite) site

We're RideTo (rideto.com), a UK marketplace for booking motorcycle training. We recently moved some pages from a server-rendered Django site to a React/Vite single-page app. Since then, organic clicks on our main course page have dropped about 35% quarter on quarter, while comparable legacy pages grew over the same period. We've found two likely causes and need an independent expert to confirm them, size them, and tell us exactly what to fix: 1. Google may not be able to load our JS and CSS. Our asset domain (static.rideto.com, S3 + CloudFront) returns 403 for robots.txt. Search Console's live test reports most JS, CSS and font files as "blocked by robots.txt" and shows around 50 CORS errors. The rendered screenshot is close to blank. 2. The pages are client-side rendered only. The raw HTML contains an empty root div with almost no text or links. All content is built by JavaScript in the browser. What we need: - A clear diagnosis of both issues: what is actually happening for Googlebot and for AI crawlers, how serious it is, and which matters most. - A technical SEO audit of our 7 new course pages: /cbt-training, /cbt-training-renewal, /motorcycle-licence, /a1-licence, /a2-licence, /introduction-to-motorcycling and /gear-conversion-course. Cover rendering, indexability, meta and canonical tags, structured data, internal linking and Core Web Vitals. - A recommended fix that fits our stack (Django backend, React/Vite frontend): server-side rendering, pre-rendering, or Django rendering the core content into the HTML. Include pros, cons and rough effort for each. - A prioritised action list our developers can implement directly. - A pass/fail checklist we can use to verify each page before it goes live. Must have: - Proven experience fixing JavaScript SEO and rendering problems on React, Vue or other single-page apps. - Hands-on experience with Search Console URL Inspection, rendered-HTML debugging, and CDN, CORS and robots.txt issues. - Clear written English for a mixed audience of product and engineering.