ci: add setup-node@v4 to deploy-public build job

Microsoft.TypeScript.MSBuild requires node on PATH during dotnet publish.
Without an explicit setup step, TS compilation silently skips on runners
that don't pre-install Node, leaving wwwroot/js/audio/ empty in the artifact.

.gitea/workflows/deploy-public.yml

@@ -21,6 +21,10 @@ jobs:
         with:
           dotnet-version: '10.0.x'
 
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
       - name: Install wasm-tools workload
         run: dotnet workload install wasm-tools