feat: scaffold Nuxt 3 + Nuxt UI 3

Initialize Nuxt 4 project with @nuxt/ui template including Tailwind CSS v4,
TypeScript, ESLint, and Nuxt UI v3 (via @nuxt/ui package).

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

front-end/app/assets/css/main.css

@@ -0,0 +1,18 @@
+@import "tailwindcss";
+@import "@nuxt/ui";
+
+@theme static {
+  --font-sans: 'Public Sans', sans-serif;
+
+  --color-green-50: #EFFDF5;
+  --color-green-100: #D9FBE8;
+  --color-green-200: #B3F5D1;
+  --color-green-300: #75EDAE;
+  --color-green-400: #00DC82;
+  --color-green-500: #00C16A;
+  --color-green-600: #00A155;
+  --color-green-700: #007F45;
+  --color-green-800: #016538;
+  --color-green-900: #0A5331;
+  --color-green-950: #052E16;
+}