Fix guides for vibe-coded apps

The breakages we see most in apps built with Cursor, Lovable, Bolt, Replit, and v0, with the steps to fix each one yourself.

• Supabase RLS not working in your Lovable, Bolt, or Cursor appUsers can see each other's data, or every query returns nothing. How to check and fix Supabase Row Level Security in an AI-built app.
• Stripe checkout works but the user is still on the free planPayment succeeds, the plan never unlocks. How to debug Stripe webhooks in an AI-built app: signature errors, wrong secret, raw body, and missing events.
• Environment variables undefined after deployWorks locally, breaks on Vercel or Netlify with undefined API keys. Why env vars go missing in AI-built apps and how to fix them safely.
• Blank white screen after deployThe preview looked fine, the live site is a white page. How to find the real error behind a blank screen in a React, Vite, or Next.js app built with AI.
• Vercel or Netlify deploy fails but it builds locallyBuild passes on your laptop, fails on the host. The common reasons AI-built apps fail to deploy and how to fix each one.