feat(agent): 经验记忆 - 按任务相关度排序召回，并过期清理待批准记忆

召回按主题、情境和中文双字命中加权；30天未处理的待批准记忆会在记录和压缩调度时过期，成功计数写入运行态以免事件窗口截断后误拦。

backend/internal/app/cloud_agent_runtime_state.go

@@ -142,6 +142,9 @@ func validateCloudAgentRuntime(run *model.CloudAgentExecution, state *cloudAgent
 	if state.Step < 0 || state.Generations < 0 || state.VideoSeconds < 0 {
 		return errors.New("Agent runtime budget or step is invalid")
 	}
+	if state.LessonEligibleToolSuccesses < 0 || state.RememberLessonSuccesses < 0 {
+		return errors.New("Agent lesson success counters are invalid")
+	}
 	if state.ConfirmationRounds < 0 || state.ConfirmationRounds > cloudAgentMaxConfirmationRounds {
 		return errors.New("Agent runtime confirmation round is invalid")
 	}