feat: turbostarter boilerplate

Production-ready Next.js boilerplate with:
- Runtime env validation (fail-fast on missing vars)
- Feature-gated config (S3, Stripe, email, OAuth)
- Docker + Coolify deployment pipeline
- PostgreSQL + pgvector, MinIO S3, Better Auth
- TypeScript strict mode (no ignoreBuildErrors)
- i18n (en/es), AI modules, billing, monitoring

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/postcss.config.mjs

@@ -0,0 +1,6 @@
+/** @type {import('postcss').ProcessOptions} */
+export default {
+  plugins: {
+    "@tailwindcss/postcss": {},
+  },
+};