chore: 移除 AiStart.java 中未使用的 Logger

清理之前添加诊断代码时引入的 Logger 导入和声明。

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: CodeCasterX

framework/fel/java/fel-flow/src/main/java/modelengine/fel/engine/activities/AiStart.java

@@ -45,7 +45,6 @@
 import modelengine.fit.waterflow.domain.stream.reactive.Publisher;
 import modelengine.fit.waterflow.domain.utils.Tuple;
 import modelengine.fitframework.inspection.Validation;
-import modelengine.fitframework.log.Logger;
 import modelengine.fitframework.util.ObjectUtils;
 
 import java.util.ArrayList;
@@ -67,7 +66,6 @@
  * @since 2024-04-28
  */
 public class AiStart<O, D, I, RF extends Flow<D>, F extends AiFlow<D, RF>> extends AiActivity<D, RF, F> {
-    private static final Logger log = Logger.get(AiStart.class);
     private final Start<O, D, I, RF> start;
 
     /**