Hardcoded backend URL in short-link form breaks non-production environments

[ianujvarshney]

File: frontend/components/ui/ShortURL.jsx (line 13)

Title

Make the short-link API URL configurable

Issue description

The short-link form posts directly to a hardcoded DigitalOcean backend URL and also builds the returned short URL with that same host. This makes the frontend difficult to run locally or point at staging and can silently break if the backend domain changes.

Expected

• Read API base URL from environment variables
• Use the same configurable base for both request and generated short URL
• Show user-friendly loading and error states

Acceptance criteria

• The form works in local, staging, and production environments
• No backend host is hardcoded in the component
• Failed requests display a visible error