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>

.gitignore

@@ -0,0 +1,41 @@
+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/versions
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+.pnpm-debug.log*
+
+# env files (can opt-in for committing if needed)
+.env*
+
+# vercel
+.vercel
+
+# typescript
+*.tsbuildinfo
+next-env.d.ts