refactor(app): 修改设备加载工作器的执行周期

- 将 LoadDeviceWorker 的执行周期从30 分钟改为 30 秒
- 删除了 .idea/misc.xml 文件中的 XML 声明

.idea/misc.xml

@@ -1,4 +1,3 @@
-<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="FrameworkDetectionExcludesConfiguration">

app/src/main/java/com/example/retention/MainActivity.java

@@ -202,7 +202,7 @@ public class MainActivity extends AppCompatActivity {
 
   private void startLoadWork() {
     PeriodicWorkRequest workRequest = new PeriodicWorkRequest.
-        Builder(LoadDeviceWorker.class, 30, TimeUnit.MINUTES)
+        Builder(LoadDeviceWorker.class, 30, TimeUnit.SECONDS)
         .setInitialDelay(0, TimeUnit.SECONDS)
         .addTag(WORK_TAG)
         .build();