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/.editorconfig

@@ -0,0 +1,13 @@
+# editorconfig.org
+root = true
+
+[*]
+indent_size = 2
+indent_style = space
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false