fix: the navigation bar stays dark when the launcher is not fullscreen

From Android 14 the Material theme leaves the navigation bar
transparent, so with launcher fullscreen off a white system bar showed
under the dark launcher. AppTheme now sets the navigation bar to black,
matching the status bar.

app/src/main/res/values/themes.xml

@@ -2,6 +2,7 @@
 <resources>
     <style name="AppTheme" parent="@android:style/Theme.Material.NoActionBar">
         <item name="android:colorBackground">#FF101418</item>
+        <item name="android:navigationBarColor">@android:color/black</item>
     </style>
     <style name="SessionTheme" parent="@android:style/Theme.Material.NoActionBar.Fullscreen">
         <item name="android:windowBackground">@android:color/black</item>

app/src/test/java/com/droiddeck/launcher/ui/AppThemeTest.kt

@@ -0,0 +1,25 @@
+package com.droiddeck.launcher.ui
+
+import android.graphics.Color
+import android.view.ContextThemeWrapper
+import com.droiddeck.launcher.R
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.RuntimeEnvironment
+import org.robolectric.annotation.Config
+
+@RunWith(RobolectricTestRunner::class)
+@Config(sdk = [34])
+class AppThemeTest {
+    @Test fun theNavigationBarIsOpaqueAndDarkSoNothingLightShowsThroughIt() {
+        val themed = ContextThemeWrapper(RuntimeEnvironment.getApplication(), R.style.AppTheme)
+        val attrs = themed.obtainStyledAttributes(intArrayOf(android.R.attr.navigationBarColor))
+        val color = attrs.getColor(0, Color.TRANSPARENT)
+        attrs.recycle()
+        assertEquals(0xFF, Color.alpha(color))
+        assertTrue(Color.luminance(color) < 0.1f)
+    }
+}