Improve Payload media: async alt text, un-cropped thumbnails, AVIF support, PDF blocking

Replace Cloudflare Turnstile with Vercel BotID

Rename to payload-starter — strip Sanity, CLI, and dead weight

Switch to on-demand revalidation + update CLAUDE.md

Simplify migration docs — standard Payload workflow, no manual SQL

Remove custom hooks + enable direct Blob URLs

Simplify favicon to Next.js file convention

Remove env var fallback for GA ID — CMS only

Read Google Analytics ID from CMS and inject custom head/body scripts

Add PostHog analytics with automatic pageview tracking

Don't save alt text from API — let user save via Payload UI

Move Generate Alt Text button below the alt text field

Use Payload's native Button component for Generate Alt Text

Regenerate import map for GenerateAltTextButton

Hide Generate Alt Text button from media list view