feat: scaffold monorepo with Go backend + Next.js 15 frontend

- Root monorepo: /backend (Go) + /frontend (Next.js 15)
- Go module: mgit.msbls.de/m/KanzlAI with minimal HTTP server
- Next.js 15: TypeScript strict, Tailwind CSS v4, App Router, Bun
- Root Makefile: dev, build, lint, test targets
- Root .gitignore covering Go, Node, IDE, OS files
- CLAUDE.md updated with project structure and tech stack
- .claude/CLAUDE.md with coding conventions (Go stdlib style, TS strict)

README.md

@@ -1,3 +1,37 @@
 # KanzlAI
 
-AI-powered law firm tools
+AI-powered toolkit for patent litigation — starting with UPC case law search and analysis.
+
+## Structure
+
+```
+backend/     Go API server
+frontend/    Next.js 15 (TypeScript, Tailwind CSS)
+```
+
+## Development
+
+```bash
+# Backend
+make dev-backend
+
+# Frontend
+make dev-frontend
+
+# Build all
+make build
+
+# Lint all
+make lint
+
+# Test all
+make test
+```
+
+## Tech Stack
+
+- **Frontend:** Next.js 15, TypeScript, Tailwind CSS
+- **Backend:** Go
+- **Database:** Supabase (PostgreSQL)
+- **AI:** Claude API
+- **Deploy:** mRiver + Caddy