feat: setup frontend con pnpm, vite, react, tailwind y shadcn

Inicializa directorio frontend/ con stack React moderno:
pnpm + vite 8 + react 19 + tailwind v4 + shadcn v4 (base-nova).
Estructura functions/core (TS puro) y functions/ui (componentes React).
El indexer descubre frontend/functions/ y frontend/types/ automáticamente.
Elimina functions/components/ (legacy) y actualiza referencias en
CLAUDE.md y template de componentes.

frontend/vite.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from "vite";
+import react from "@vitejs/plugin-react";
+import tailwindcss from "@tailwindcss/vite";
+import path from "path";
+
+export default defineConfig({
+  plugins: [react(), tailwindcss()],
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "./src"),
+    },
+  },
+});