Consolidate to single server with unified package.json

- Merge client and server dependencies into root package.json
- Remove separate client/package.json and server/package.json
- Update server/index.js to serve built client static files
- Simplify Dockerfile to single build + production stage
- Update dev scripts for unified development workflow
- SPA routing serves index.html for non-API routes

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

package.json

@@ -4,15 +4,45 @@
   "description": "T-shirt customization editor with background removal, stickers, text, and export",
   "private": true,
   "type": "module",
+  "main": "server/index.js",
   "scripts": {
-    "postinstall": "cd client && npm install && cd ../server && npm install",
     "dev": "concurrently \"npm run dev:client\" \"npm run dev:server\"",
-    "dev:client": "cd client && npm run dev",
-    "dev:server": "cd server && npm run dev",
-    "build": "cd client && npm run build",
-    "start": "node server/index.js"
+    "dev:client": "cd client && vite",
+    "dev:server": "node --watch server/index.js",
+    "build": "cd client && vite build",
+    "start": "node server/index.js",
+    "install:all": "npm install && cd client && npm install"
+  },
+  "dependencies": {
+    "canvas": "^2.11.2",
+    "cors": "^2.8.5",
+    "express": "^4.18.2",
+    "multer": "^1.4.5-lts.1",
+    "sharp": "^0.33.2",
+    "uuid": "^9.0.1"
   },
   "devDependencies": {
-    "concurrently": "^8.2.0"
+    "@eslint/js": "^9.39.4",
+    "@types/react": "^19.2.14",
+    "@types/react-dom": "^19.2.3",
+    "@vitejs/plugin-react": "^6.0.1",
+    "concurrently": "^8.2.0",
+    "eslint": "^9.39.4",
+    "eslint-plugin-react-hooks": "^7.1.1",
+    "eslint-plugin-react-refresh": "^0.5.2",
+    "globals": "^17.5.0",
+    "vite": "^8.0.9",
+    "vite-plugin-pwa": "^0.20.5",
+    "workbox-window": "^7.1.0",
+    "react": "^19.2.5",
+    "react-dom": "^19.2.5",
+    "react-konva": "^18.2.10",
+    "konva": "^9.3.18",
+    "use-image": "^1.1.1",
+    "@xenova/transformers": "^2.17.2",
+    "react-filerobot-image-editor": "^4.8.1"
+  },
+  "engines": {
+    "node": ">=20.0.0"
   }
 }