Initial commit: Estructura backend y frontend con estándar VPS

- Backend migrado a estructura VPS (src/ subfolder)
- Frontend con estructura Vite + React 19 + Tailwind
- Configuración PostgreSQL con Pool
- API service con interceptores JWT
- Ambos servidores funcionando (backend:3001, frontend:5173)

backend/package.json

@@ -0,0 +1,41 @@
+{
+  "name": "ofertaweb-backend",
+  "version": "1.0.0",
+  "description": "Backend API para tienda web multi-canal",
+  "main": "server.js",
+  "scripts": {
+    "start": "node server.js",
+    "dev": "nodemon server.js",
+    "test": "jest --coverage"
+  },
+  "keywords": [
+    "ecommerce",
+    "api",
+    "mercadolibre",
+    "instagram"
+  ],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "axios": "^1.6.2",
+    "bcryptjs": "^2.4.3",
+    "cors": "^2.8.5",
+    "dotenv": "^17.2.3",
+    "express": "^5.2.1",
+    "joi": "^17.11.0",
+    "jsonwebtoken": "^9.0.2",
+    "mercadolibre": "^0.0.13",
+    "multer": "^1.4.5-lts.1",
+    "node-cron": "^3.0.3",
+    "nodemailer": "^6.9.7",
+    "pg": "^8.16.3",
+    "sharp": "^0.33.1",
+    "winston": "^3.11.0",
+    "helmet": "^7.1.0"
+  },
+  "devDependencies": {
+    "jest": "^29.7.0",
+    "nodemon": "^3.0.2",
+    "supertest": "^6.3.3"
+  }
+}