feat: Initial implementation of Annas Rechnungsmanager

Full-stack German accounting & invoice management web application:

- Multi-company management (Mandantenverwaltung) with full CRUD
- Invoice creation with dynamic line items and automatic tax calculation
- Sequential invoice numbering per company (RE-2024-001 format)
- §14 UStG compliant PDF invoice generation via @react-pdf/renderer
- Customer management (Kundenverwaltung) per company
- Tax reports: quarterly USt-Voranmeldung and monthly revenue overview
- Email/password authentication via NextAuth.js v5
- Responsive, modern UI with Tailwind CSS and custom shadcn/ui components
- Prisma v5 ORM with MySQL/MariaDB schema + demo seed data

Stack: Next.js 14 (App Router) · TypeScript · Prisma/MySQL · NextAuth.js

https://claude.ai/code/session_01FN53KKxo5ebrGwqFhxzkT9

eslint.config.mjs

@@ -0,0 +1,18 @@
+import { defineConfig, globalIgnores } from "eslint/config";
+import nextVitals from "eslint-config-next/core-web-vitals";
+import nextTs from "eslint-config-next/typescript";
+
+const eslintConfig = defineConfig([
+  ...nextVitals,
+  ...nextTs,
+  // Override default ignores of eslint-config-next.
+  globalIgnores([
+    // Default ignores of eslint-config-next:
+    ".next/**",
+    "out/**",
+    "build/**",
+    "next-env.d.ts",
+  ]),
+]);
+
+export default eslintConfig;