Add Next.js 15 app skeleton with Tailwind v4 and shadcn/ui

Next.js 15 + React 19, Tailwind v4, shadcn/ui (button, card, input,
dialog), postcss config, standalone output. ESLint extended with
next/core-web-vitals via eslint-config-next flat export. node-linker=hoisted
in .npmrc to allow standalone builds on Windows (symlink restriction).
next-env.d.ts added to .gitignore.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

eslint.config.mjs

@@ -1,6 +1,7 @@
 import js from "@eslint/js";
 import tseslint from "typescript-eslint";
 import globals from "globals";
+import nextConfig from "eslint-config-next/core-web-vitals";
 
 export default tseslint.config(
   {
@@ -9,13 +10,11 @@ export default tseslint.config(
       ".next/**",
       "dist/**",
       "drizzle/**",
-      "*.config.js",
-      "*.config.mjs",
-      "*.config.cjs",
     ],
   },
   js.configs.recommended,
   ...tseslint.configs.recommended,
+  ...nextConfig,
   {
     languageOptions: {
       globals: {