chore: sync package.json versions to 2.2.0

backend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "picpeak-backend",
-  "version": "2.1.1",
+  "version": "2.2.0",
   "description": "Backend for PicPeak event photo sharing platform",
   "main": "server.js",
   "scripts": {

frontend/package.json

@@ -1,7 +1,7 @@
 {
   "name": "picpeak-frontend",
   "private": true,
-  "version": "2.1.1",
+  "version": "2.2.0",
   "type": "module",
   "scripts": {
     "dev": "vite",