Allow custom headers on OpenAI providers (to be added to more later)

pkg/api/provider/openai/openai.go

@@ -16,6 +16,7 @@ import (
 type OpenAIClient struct {
 	APIKey  string
 	BaseURL string
+	Headers map[string]string
 }
 
 type ChatCompletionMessage struct {
@@ -198,6 +199,9 @@ func (c *OpenAIClient) sendRequest(ctx context.Context, r ChatCompletionRequest)
 
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", "Bearer "+c.APIKey)
+	for header, val := range c.Headers {
+		req.Header.Set(header, val)
+	}
 
 	client := &http.Client{}
 	resp, err := client.Do(req)