migrate to "export default"

also, set no-use-before-define in linter

src/apptaskmanager.js

@@ -6,15 +6,11 @@ import locks from './locks.js';
 import path from 'node:path';
 import paths from './paths.js';
 import safe from 'safetydance';
-import * as scheduler from './scheduler.js';
+import scheduler from './scheduler.js';
 import tasks from './tasks.js';
 
 const debug = debugModule('box:apptaskmanager');
 
-export {
-    start,
-    scheduleTask
-};
 
 const gActiveTasks = {}; // indexed by app id
 const gPendingTasks = [];
@@ -92,3 +88,8 @@ function scheduleTask(appId, taskId, options, onFinished) {
 
     if (gStarted && !gDrainTimerId) gDrainTimerId = setTimeout(drain, DRAIN_TIMER_SECS);
 }
+
+export default {
+    start,
+    scheduleTask
+};