android: keep screen on while playing/recording media

apps/multiplatform/android/src/main/java/chat/simplex/app/SimplexApp.kt

@@ -1,6 +1,8 @@
 package chat.simplex.app
 
 import android.app.Application
+import androidx.compose.runtime.*
+import androidx.compose.ui.platform.LocalView
 import chat.simplex.common.platform.Log
 import androidx.lifecycle.*
 import androidx.work.*
@@ -216,6 +218,17 @@ class SimplexApp: Application(), LifecycleEventObserver {
         }
         return true
       }
+
+      @Composable
+      override fun AndroidKeepScreenOn() {
+        val view = LocalView.current
+        DisposableEffect(Unit) {
+          view.keepScreenOn = true
+          onDispose {
+            view.keepScreenOn = false
+          }
+        }
+      }
     }
   }
 }