ci: update Node.js from 20 to 22 LTS

Node 20 reaches EOL April 2026. Node 22 is the current active LTS.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: piti6

.github/workflows/deploy-web.yml

@@ -30,7 +30,7 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: '20'
+          node-version: '22'
           cache: 'npm'
 
       - name: Install npm dependencies