fix: support embedding models for doubao (#1662)

Fixes #1594

relay/adaptor/doubao/main.go

@@ -7,8 +7,12 @@ import (
 )
 
 func GetRequestURL(meta *meta.Meta) (string, error) {
-	if meta.Mode == relaymode.ChatCompletions {
+	switch meta.Mode {
+	case relaymode.ChatCompletions:
 		return fmt.Sprintf("%s/api/v3/chat/completions", meta.BaseURL), nil
+	case relaymode.Embeddings:
+		return fmt.Sprintf("%s/api/v3/embeddings", meta.BaseURL), nil
+	default:
 	}
 	return "", fmt.Errorf("unsupported relay mode %d for doubao", meta.Mode)
 }