Custom Request Headers

I suggest support for configuring custom HTTP request headers in Finer.

This would be useful for users running Finer behind a proxy, with special authentication requirements, or in environments where additional headers like User-Agent, X-Request-ID, or other custom headers are needed (for example with Pangolin).

Benefits

• Better support for secure deployments

• Easier debugging and request tracing

Expected behavior

• Users can define custom headers in app settings

• Headers are included in requests to Jellyfin

• Default behavior remains unchanged if no headers are set