Move app state banner to the very top (#8706)

This moves the banners to the root composable and so eliminates the need to
track the app states in every screen.

app/src/main/java/eu/kanade/presentation/components/Banners.kt

@@ -3,8 +3,13 @@ package eu.kanade.presentation.components
 import androidx.annotation.StringRes
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.WindowInsets
+import androidx.compose.foundation.layout.WindowInsetsSides
 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.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
@@ -37,24 +42,34 @@ fun AppStateBanners(
     incognitoMode: Boolean,
     modifier: Modifier = Modifier,
 ) {
+    val insets = WindowInsets.systemBars.only(WindowInsetsSides.Top + WindowInsetsSides.Horizontal)
     Column(modifier = modifier) {
         if (downloadedOnlyMode) {
-            DownloadedOnlyModeBanner()
+            DownloadedOnlyModeBanner(
+                modifier = Modifier.windowInsetsPadding(insets),
+            )
         }
         if (incognitoMode) {
-            IncognitoModeBanner()
+            IncognitoModeBanner(
+                modifier = if (!downloadedOnlyMode) {
+                    Modifier.windowInsetsPadding(insets)
+                } else {
+                    Modifier
+                },
+            )
         }
     }
 }
 
 @Composable
-private fun DownloadedOnlyModeBanner() {
+private fun DownloadedOnlyModeBanner(modifier: Modifier = Modifier) {
     Text(
         text = stringResource(R.string.label_downloaded_only),
         modifier = Modifier
             .background(color = MaterialTheme.colorScheme.tertiary)
             .fillMaxWidth()
-            .padding(4.dp),
+            .padding(4.dp)
+            .then(modifier),
         color = MaterialTheme.colorScheme.onTertiary,
         textAlign = TextAlign.Center,
         style = MaterialTheme.typography.labelMedium,
@@ -62,13 +77,14 @@ private fun DownloadedOnlyModeBanner() {
 }
 
 @Composable
-private fun IncognitoModeBanner() {
+private fun IncognitoModeBanner(modifier: Modifier = Modifier) {
     Text(
         text = stringResource(R.string.pref_incognito_mode),
         modifier = Modifier
             .background(color = MaterialTheme.colorScheme.primary)
             .fillMaxWidth()
-            .padding(4.dp),
+            .padding(4.dp)
+            .then(modifier),
         color = MaterialTheme.colorScheme.onPrimary,
         textAlign = TextAlign.Center,
         style = MaterialTheme.typography.labelMedium,