fix: set TopP to nil in Claude request configuration

relay/channel/claude/relay-claude.go

@@ -160,7 +160,7 @@ func RequestOpenAI2ClaudeMessage(c *gin.Context, textRequest dto.GeneralOpenAIRe
 			Type: "adaptive",
 		}
 		claudeRequest.OutputConfig = json.RawMessage(fmt.Sprintf(`{"effort":"%s"}`, effortLevel))
-		claudeRequest.TopP = common.GetPointer[float64](0)
+		claudeRequest.TopP = nil
 		claudeRequest.Temperature = common.GetPointer[float64](1.0)
 	} else if model_setting.GetClaudeSettings().ThinkingAdapterEnabled &&
 		strings.HasSuffix(textRequest.Model, "-thinking") {