Initial project structure: Next.js 15 + TypeScript + Drizzle ORM

- Next.js 15 with App Router, TypeScript, Tailwind CSS
- Directory structure per LegalAI architecture plan
- Docker Compose setup (PostgreSQL 16, Meilisearch, App)
- Drizzle ORM with base schema (tenants, users, norms, decisions)
- AI abstraction layer structure (Vercel AI SDK)
- Normen-Engine with Quellenrang hierarchy
- Search abstraction layer
- Auth placeholder (NextAuth.js)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

postcss.config.mjs

@@ -0,0 +1,7 @@
+const config = {
+  plugins: {
+    "@tailwindcss/postcss": {},
+  },
+};
+
+export default config;