fix: continue pipeline when npm cache fails on Gitea runner

Add continue-on-error: true to setup-node step to prevent cascade
failure when act-based runner cannot resolve cache-dependency-path.

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

.gitea/workflows/nextjs-deploy.yaml

@@ -29,6 +29,7 @@ jobs:
 
       - name: 🟢 Setup Node 20 + Cache
         uses: actions/setup-node@v4
+        continue-on-error: true
         with:
           node-version: 20
           cache: "npm"