fix: Remove npm cache from CI workflow

Gitea Actions runner hangs on npm cache config. Removing
cache option to fix CI pipeline.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitea/workflows/build.yml

@@ -27,7 +27,6 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: '20'
-          cache: 'npm'
 
       - name: Install dependencies
         run: npm ci