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>

.context/turbostarter-framework-context/sections/web/billing/creem.md

@@ -0,0 +1,13 @@
+---
+title: Creem
+description: Manage your customers data and subscriptions using Creem.
+url: /docs/web/billing/creem
+---
+
+# Creem
+
+<Callout title="Creem integration is coming soon!">
+  We are working on adding [Creem](https://www.creem.io/) integration to our platform. As soon as it's ready, we will update this page with the necessary information.
+
+  [See roadmap](https://github.com/orgs/turbostarter/projects/1)
+</Callout>