fix(openrouter): use xstrings helper

Co-authored-by: Andrey Nering <andreynering@users.noreply.github.com>

Author: meowgorithm

providers/openrouter/language_model_hooks.go

@@ -295,8 +295,7 @@ func languageModelStreamExtra(chunk openaisdk.ChatCompletionChunk, yield func(fa
 		currentState.format = detail.Format
 		ctx[reasoningStartedCtx] = currentState
 		delta := detail.Summary
-		if strings.HasPrefix(detail.Format, "google-gemini") ||
-			strings.HasPrefix(detail.Format, "anthropic-claude") {
+		if xstrings.ContainsAnyOf(detail.Format, "google-gemini", "anthropic-claude") {
 			delta = detail.Text
 		}
 		return ctx, yield(fantasy.StreamPart{