Add backend package.json with dependencies

backend/package.json

@@ -0,0 +1,28 @@
+{
+  "name": "pnger-backend",
+  "version": "1.0.0",
+  "description": "PNG editor backend API",
+  "main": "src/server.js",
+  "scripts": {
+    "start": "node src/server.js",
+    "dev": "nodemon src/server.js",
+    "test": "echo \"No tests yet\" && exit 0"
+  },
+  "keywords": ["png", "image", "editor", "resize"],
+  "author": "jason",
+  "license": "MIT",
+  "dependencies": {
+    "express": "^4.18.2",
+    "multer": "^1.4.5-lts.1",
+    "sharp": "^0.33.2",
+    "cors": "^2.8.5",
+    "helmet": "^7.1.0",
+    "dotenv": "^16.4.1"
+  },
+  "devDependencies": {
+    "nodemon": "^3.0.3"
+  },
+  "engines": {
+    "node": ">=20.0.0"
+  }
+}