ai-refactor(flow): 调整抽象流程节点实现和依赖路径

- 修改 AbstractProcessNode 中 ProcessContext 的命名空间引用为 app\flow\context\ProcessContext
- 引入 app\flow\vo\CanHandleResult 用于节点处理结果表示
- 更新前置策略执行后对成功状态的判断，改为调用 isSuccess() 方法
- 增加日志记录细节，便于调试策略执行中断时的错误信息
- 优化代码注释，提升代码可读性和维护性

app/flow/ProcessEngine.php

@@ -174,22 +174,22 @@ class ProcessEngine
     public function execute(ProcessContext $context): ProcessContext
     {
         if ($this->chainHead === null) {
-            return $context->setError(VoiceMessage::PROCESS_CHAIN_NOT_INITIALIZED);
+            return $context->builder()->error(VoiceMessage::PROCESS_CHAIN_NOT_INITIALIZED)->build();
         }
     
         Logger::debug('[ProcessEngine] 开始执行流程链 readerType={} currentStep={} endoscope={}', [
-            $context->readerType,
-            $context->currentStep ?: '(空)',
-            $context->endoscopeName ?: $context->endoscopeId ?: '-',
+            $context->getReader()->type,
+            $context->getCurrentStep() ?: '(空)',
+            $context->getEndoscope()->name ?: $context->getEndoscope()->id ?: '-',
         ]);
     
         $result = $this->chainHead->handle($context);
 
         Logger::debug('[ProcessEngine] 流程执行完成 endoscope={} step={} success={} error={}', [
-            $result->endoscopeName,
-            $result->currentStep,
-            $result->success ? 'true' : 'false',
-            $result->errorMessage->value ?: '-',
+            $result->getEndoscope()->name,
+            $result->getCurrentStep(),
+            $result->isSuccess() ? 'true' : 'false',
+            $result->getVoice()->errorMessage->value ?: '-',
         ]);
     
         return $result;