feat: do not send origin header to ollama

Currently the request to Ollama contains `Origin: null` header, which is not accepted by Ollama server (server responds with 403).

There seem to be a way to remove Origin header, by setting it's value to an empty string.

fixes:
- gitbutlerapp#8078
- gitbutlerapp#5862

ref:
- tauri-apps/plugins-workspace#1941
- https://github.com/ollama/ollama-js/blob/6a4bfe3ab033f611639dfe4249bdd6b9b19c7256/src/browser.ts#L38
- https://github.com/gitbutlerapp/gitbutler/blob/9af0e4bbaa845aeb40a82f22ad66975a61990654/Cargo.lock#L8431

Author: mochja

apps/desktop/src/lib/ai/ollamaClient.ts

@@ -53,7 +53,10 @@ export class OllamaClient implements AIClient {
 		private modelName: string
 	) {
 		this.ollama = new Ollama({
-			host: this.endpoint
+			host: this.endpoint,
+			headers: {
+				origin: ''
+			}
 		});
 	}