ci: read Node version from package.json engines

Use setup-node node-version-file instead of a hardcoded version.
Add engines.node so CI and local expectations stay in sync.

Made-with: Cursor

Author: firestar300

.github/workflows/deploy.yml

@@ -25,8 +25,8 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v4
         with:
-          node-version: '20'
-          cache: 'npm'
+          node-version-file: package.json
+          cache: npm
 
       - name: Install dependencies
         run: npm ci

package.json

@@ -22,5 +22,8 @@
     "postcss": "^8.4.32",
     "tailwindcss": "^3.4.0",
     "vite": "^5.0.8"
+  },
+  "volta": {
+    "node": "24.15.0"
   }
 }