chore: projekt-scaffold mit next 15, tailwind und shadcn/ui

Next.js 15 (App Router, TypeScript strict), Tailwind CSS 4 und
shadcn/ui als Basis. Standalone-Output und serverExternalPackages
sind fuer den spaeteren Docker-Build vorbereitet.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

eslint.config.mjs

@@ -0,0 +1,25 @@
+import { dirname } from "path";
+import { fileURLToPath } from "url";
+import { FlatCompat } from "@eslint/eslintrc";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+const compat = new FlatCompat({
+  baseDirectory: __dirname,
+});
+
+const eslintConfig = [
+  ...compat.extends("next/core-web-vitals", "next/typescript"),
+  {
+    ignores: [
+      "node_modules/**",
+      ".next/**",
+      "out/**",
+      "build/**",
+      "next-env.d.ts",
+    ],
+  },
+];
+
+export default eslintConfig;