🐞 Bug Summary

MCP Registry "Add Server" button behaviour is inconsistent. The spinner won't replace the original text, and - as the POST route's response is a JSON object - the actual button is gone and replaced with a layout-braking JSON object when the server is added successfully (see screenshots below).

🧩 Affected Component

Select the area of the project impacted:

• mcpgateway - API
• mcpgateway - UI (admin panel)
• mcpgateway.wrapper - stdio wrapper
• Federation or Transports
• CLI, Makefiles, or shell scripts
• Container setup (Docker/Podman/Compose)
• Other (explain below)

🔁 Steps to Reproduce

1. Access the Admin UI
2. Click the MCP Registry tab
3. Add a few servers, with multiple auth settings (open, OAuth2, api...)

🤔 Expected Behavior

• For Auth servers, a modal should open for configuring it.
• While the server is being added, the button label should be replaced with the spinner
• After the server is added, the button should be replaced with the disabled version with the "Already registered" label