fix(mcp): respect configured package registry

Closes #5912

apps/desktop/src/components/editor/EditorSettingsDialog.vue

@@ -1816,7 +1816,7 @@ const mcpStatusLabel = computed(() => {
 });
 
 const mcpCommand = computed(() => {
-  if (!mcpStatus.value) return "npm install -g @dbx-app/mcp-server@latest --registry=https://registry.npmjs.org";
+  if (!mcpStatus.value) return "npm install -g @dbx-app/mcp-server@latest";
   return mcpStatus.value.installed ? mcpStatus.value.update_command : mcpStatus.value.install_command;
 });