@tailwindcss/postcss lives in devDependencies (along with the rest of
the PostCSS toolchain). When NODE_ENV=production is set in the Amplify
build environment, npm ci skips devDependencies — and next build then
fails resolving @tailwindcss/postcss while compiling globals.css.
amplify.yml now passes --include=dev to npm ci so the build always
installs everything regardless of NODE_ENV. AMPLIFY_DEPLOY.md updated
to warn against setting NODE_ENV=production in the Amplify env vars
panel — it's redundant (Next sets it correctly) and an easy footgun.
- amplify.yml: build spec (preBuild npm ci with offline cache, build
next build, artifacts at .next/**, cache node_modules/.next-cache/.npm).
- .nvmrc: pin Node 20 so Amplify uses the same runtime as local.
- AMPLIFY_DEPLOY.md: first-time walkthrough covering AWS-side setup
(create app, connect GitHub via OAuth/App, branch/auto-detect),
environment variable table with secret-flag guidance, smoke-test via
/healthz and /api/health, optional custom domain + per-PR previews,
cost estimate, and operational notes (cold starts, no static
egress IPs, CloudWatch logs, secret rotation).
- README deploy section: now points at both AMPLIFY_DEPLOY.md and the
existing DEPLOYMENT.md (Render).