Custom Headers for Ollama

[pkkulhari]

It would be convenient if the Ollama settings included an option to set custom headers.

This feature would be handy when Ollama is deployed behind a proxy. In my case, I have Ollama running with an ngrok reverse proxy, which requires the header "Ngrok-Skip-Browser-Warning" to function properly.

I’d be happy to submit a pull request to implement these changes.