Migrate reader low brightness overlay to Compose

(cherry picked from commit d9c0b1ce7d1739da3945622f2d18b171a471fc2e)

# Conflicts:
#	app/src/main/java/eu/kanade/presentation/reader/appbars/ReaderAppBars.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt
#	app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderViewModel.kt

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

@@ -0,0 +1,26 @@
+package eu.kanade.presentation.reader
+
+import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.graphicsLayer
+import kotlin.math.abs
+
+@Composable
+fun BrightnessOverlay(
+    value: Int,
+) {
+    if (value >= 0) return
+
+    Canvas(
+        modifier = Modifier
+            .fillMaxSize()
+            .graphicsLayer {
+                alpha = abs(value) / 100f
+            }
+    ) {
+        drawRect(Color.Black)
+    }
+}

app/src/main/java/eu/kanade/presentation/reader/appbars/ReaderAppBars.kt

@@ -13,14 +13,10 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxScope
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.WindowInsets
-import androidx.compose.foundation.layout.WindowInsetsSides
 import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.only
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.systemBars
-import androidx.compose.foundation.layout.windowInsetsPadding
+import androidx.compose.foundation.layout.systemBarsPadding
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.surfaceColorAtElevation
 import androidx.compose.runtime.Composable
@@ -114,7 +110,7 @@ fun ReaderAppBars(
     onClickChapterList: () -> Unit,
     onClickPageLayout: () -> Unit,
     onClickShiftPage: () -> Unit,
-
+    // SY <--
 ) {
     val isRtl = viewer is R2LPagerViewer
     val backgroundColor = MaterialTheme.colorScheme
@@ -122,9 +118,7 @@ fun ReaderAppBars(
         .copy(alpha = if (isSystemInDarkTheme()) 0.9f else 0.95f)
 
     val appBarModifier = if (fullscreen) {
-        // SY -->
-        Modifier.windowInsetsPadding(WindowInsets.systemBars.only(WindowInsetsSides.Top + WindowInsetsSides.Horizontal))
-        // SY <--
+        Modifier.systemBarsPadding()
     } else {
         Modifier
     }