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)

frontend/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "frontend",
+  "version": "0.1.0",
+  "private": true,
+  "scripts": {
+    "dev": "next dev --turbopack",
+    "build": "next build --turbopack",
+    "start": "next start",
+    "lint": "eslint"
+  },
+  "dependencies": {
+    "react": "19.1.0",
+    "react-dom": "19.1.0",
+    "next": "15.5.14"
+  },
+  "devDependencies": {
+    "typescript": "^5",
+    "@types/node": "^20",
+    "@types/react": "^19",
+    "@types/react-dom": "^19",
+    "@tailwindcss/postcss": "^4",
+    "tailwindcss": "^4",
+    "eslint": "^9",
+    "eslint-config-next": "15.5.14",
+    "@eslint/eslintrc": "^3"
+  }
+}