llm/ant: replace fmt.Printf with slog in retry logic

Breaks termui.

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/llm/ant/ant.go b/llm/ant/ant.go
index dce17f1..d1c366a 100644
--- a/llm/ant/ant.go
+++ b/llm/ant/ant.go
@@ -399,7 +399,7 @@
 				return nil, err
 			}
 			if response.StopReason == "max_tokens" && !largerMaxTokens {
-				fmt.Printf("Retrying Anthropic API call with larger max tokens size.")
+				slog.InfoContext(ctx, "anthropic_retrying_with_larger_tokens", "message", "Retrying Anthropic API call with larger max tokens size")
 				// Retry with more output tokens.
 				largerMaxTokens = true
 				response.Usage.CostUSD = response.TotalDollars()