fix(anthropic): remove top_p parameter for Claude 4.5 models

Fixes #520.

src/engine/anthropic.ts

@@ -37,9 +37,14 @@ export class AnthropicEngine implements AiEngine {
       system: systemMessage,
       messages: restMessages,
       temperature: 0,
-      top_p: 0.1,
       max_tokens: this.config.maxTokensOutput
     };
+
+    // add top_p for non-4.5 models
+    if (!params.model.includes('-4-5')) {
+      params.top_p = 0.1;
+    }
+
     try {
       const REQUEST_TOKENS = messages
         .map((msg) => tokenCount(msg.content as string) + 4)