Tweak page flashing

Closes #10269, maybe. I don't really have something to test with.

app/src/main/java/eu/kanade/presentation/reader/DisplayRefreshHost.kt

@@ -30,7 +30,7 @@ fun DisplayRefreshHost(
     val currentDisplayRefresh = hostState.currentDisplayRefresh
     LaunchedEffect(currentDisplayRefresh) {
         if (currentDisplayRefresh) {
-            delay(200)
+            delay(1500)
             hostState.currentDisplayRefresh = false
         }
     }
@@ -39,7 +39,7 @@ fun DisplayRefreshHost(
         Canvas(
             modifier = modifier.fillMaxSize(),
         ) {
-            drawRect(Color.White)
+            drawRect(Color.Black)
         }
     }
 }

i18n/src/commonMain/resources/MR/base/strings.xml

@@ -350,7 +350,7 @@
     <string name="pref_double_tap_zoom">Double tap to zoom</string>
     <string name="pref_cutout_short">Show content in cutout area</string>
     <string name="pref_page_transitions">Animate page transitions</string>
-    <string name="pref_flash_page">Flash white on page change</string>
+    <string name="pref_flash_page">Flash on page change</string>
     <string name="pref_flash_page_summ">Reduces ghosting on e-ink displays</string>
     <string name="pref_double_tap_anim_speed">Double tap animation speed</string>
     <string name="pref_show_page_number">Show page number</string>