Bug

Exchange rate conversion is broken for all currency pairs. The browser blocks
the request to api.frankfurter.app due to a CORS error.

Root Cause

The Frankfurter API has migrated from api.frankfurter.app to api.frankfurter.dev.
The old domain now returns a 301 redirect to the new domain, but the redirect
response does not include the Access-Control-Allow-Origin header.
Browsers block the request before following the redirect.

Steps to Reproduce

1. Open a group
2. Add an expense with currency conversion
3. "Oops, we could not get the most recent rates. Enter a custom rate below."
4. Open the browser console → Network tab

Expected

Exchange rates load successfully.

Actual

"Oops, we could not get the most recent rates. Enter a custom rate below."