Replace vanilla HTML with React + shadcn/ui + TailwindCSS scaffold

- Frontend: React 19 + Vite + TypeScript + TailwindCSS v4 + shadcn/ui
- Pre-installed shadcn/ui components: Button, Card, Input, Separator
- Multi-stage Dockerfile: build React client → serve with Express
- Server.js updated to serve built React SPA with API routes
- Sample landing page with shadcn/ui components demonstrating usage
- Path aliases (@/) configured in tsconfig + vite config
- components.json for easy `shadcn add <component>` usage

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

package.json

@@ -1,18 +1,23 @@
 {
   "name": "template-001",
   "version": "1.0.0",
-  "description": "Template site for Start an AI Company deployment",
+  "description": "SAAC company website template — React + shadcn/ui + Express + PostgreSQL",
   "main": "server.js",
   "scripts": {
     "start": "node server.js",
-    "dev": "nodemon server.js"
+    "dev": "concurrently \"node server.js\" \"cd client && npm run dev\"",
+    "build": "cd client && npm run build",
+    "dev:server": "nodemon server.js",
+    "dev:client": "cd client && npm run dev"
   },
   "dependencies": {
     "express": "^4.18.2",
     "pg": "^8.11.3",
-    "redis": "^4.6.12"
+    "redis": "^4.6.12",
+    "cors": "^2.8.5"
   },
   "devDependencies": {
-    "nodemon": "^3.0.2"
+    "nodemon": "^3.0.2",
+    "concurrently": "^8.2.2"
   }
 }