Fix CSS build: remove @tailwindcss/postcss plugin (Next.js 16 Turbopack handles Tailwind v4 natively)

web/app/globals.css

@@ -1 +1,8 @@
 @import "tailwindcss";
+
+@layer base {
+  body {
+    -webkit-font-smoothing: antialiased;
+    -moz-osx-font-smoothing: grayscale;
+  }
+}

web/postcss.config.mjs

@@ -1,8 +1,6 @@
 /** @type {import('postcss-load-config').Config} */
 const config = {
-  plugins: {
-    "@tailwindcss/postcss": {},
-  },
+  plugins: {},
 };
 
 export default config;