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>

packages/db/turbo.json

@@ -0,0 +1,19 @@
+{
+  "$schema": "https://turborepo.org/schema.json",
+  "extends": ["//"],
+  "tasks": {
+    "db:generate": {
+      "interactive": true,
+      "cache": false,
+      "dependsOn": ["@turbostarter/auth#db:generate"]
+    },
+    "db:migrate": {
+      "cache": false
+    },
+    "db:seed": {
+      "cache": false,
+      "dependsOn": ["@turbostarter/auth#db:seed"]
+    },
+    "db:setup": {}
+  }
+}