refactor(idgen): centralize negative ID handling via panic

Restore NextUint64ID() to uint64-only API so callers need no error
checks. Retry logic stays in idgen; after 3 negative values it panics
instead of returning 0, preventing silent NULL primary keys.

internal/task/executor.go

@@ -115,10 +115,7 @@ func DispatchTask(ctx context.Context, taskType string, payload []byte, triggere
 	}
 
 	// 生成唯一的 TaskID
-	taskID, err := generateTaskID(taskType, triggeredBy)
-	if err != nil {
-		return "", err
-	}
+	taskID := generateTaskID(taskType, triggeredBy)
 
 	// 创建任务执行记录
 	execution := &model.TaskExecution{
@@ -456,12 +453,8 @@ func handleSuccessfulTask(ctx context.Context, execution *model.TaskExecution, t
 }
 
 // generateTaskID 生成任务 ID
-func generateTaskID(taskType string, triggeredBy string) (string, error) {
-	uniqueID, err := idgen.NextUint64ID()
-	if err != nil {
-		return "", err
-	}
-	return fmt.Sprintf("%s_%s_%d", triggeredBy, taskType, uniqueID), nil
+func generateTaskID(taskType string, triggeredBy string) string {
+	return fmt.Sprintf("%s_%s_%d", triggeredBy, taskType, idgen.NextUint64ID())
 }
 
 // generateRetryTaskID 生成重试任务 ID