Introduce "Black" theme and refactor theme handling

* Add `Theme.Black` to the `Theme` enum and update `isDark()` to include it.
* Refactor `ElementTheme` to accept a `Theme` object instead of a `darkTheme` boolean, allowing for more specific color mapping (e.g., setting `bgCanvasDefault` to `Color.Black` for the Black theme).
* Update `AdvancedSettingsPresenter` and `AdvancedSettingsState` to include "Black" as a user-selectable theme option.
* Adjust `ElementThemeApp` and `MaterialTextPreview` to handle the expanded theme selection.
* Add `ElementPreviewBlack` and update existing preview components to support the new theme.
* Update Konsist tests to ensure `@PreviewsDayNight` annotated functions don't have "BlackPreview" suffix.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/atomic/pages/SunsetPage.kt

@@ -31,6 +31,7 @@ import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import io.element.android.compound.annotations.CoreColorToken
 import io.element.android.compound.theme.ElementTheme
+import io.element.android.compound.theme.Theme
 import io.element.android.compound.tokens.generated.internal.DarkColorTokens
 import io.element.android.compound.tokens.generated.internal.LightColorTokens
 import io.element.android.libraries.designsystem.R
@@ -50,7 +51,7 @@ fun SunsetPage(
 ) {
     ElementTheme(
         // Always use the opposite value of the current theme
-        darkTheme = ElementTheme.isLightTheme,
+        theme = if (ElementTheme.isLightTheme) Theme.Dark else Theme.Light,
         applySystemBarsUpdate = false,
     ) {
         Box(

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/ElementPreview.kt

@@ -19,6 +19,7 @@ import coil3.asImage
 import coil3.compose.AsyncImagePreviewHandler
 import coil3.compose.LocalAsyncImagePreviewHandler
 import io.element.android.compound.theme.ElementTheme
+import io.element.android.compound.theme.Theme
 import io.element.android.libraries.designsystem.theme.components.Surface
 import io.element.android.libraries.designsystem.utils.CommonDrawables
 
@@ -26,7 +27,7 @@ import io.element.android.libraries.designsystem.utils.CommonDrawables
 @Composable
 @Suppress("ModifierMissing")
 fun ElementPreview(
-    darkTheme: Boolean = isSystemInDarkTheme(),
+    theme: Theme = if (isSystemInDarkTheme()) Theme.Dark else Theme.Light,
     showBackground: Boolean = true,
     @DrawableRes
     drawableFallbackForImages: Int = CommonDrawables.sample_background,
@@ -38,7 +39,7 @@ fun ElementPreview(
             ResourcesCompat.getDrawable(context.resources, drawableFallbackForImages, null)!!.asImage()
         }
     ) {
-        ElementTheme(darkTheme = darkTheme) {
+        ElementTheme(theme = theme) {
             if (showBackground) {
                 // If we have a proper contentColor applied we need a Surface instead of a Box
                 Surface(content = content)

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/ElementPreviewBlack.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ * Copyright 2023-2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.designsystem.preview
+
+import androidx.compose.runtime.Composable
+import io.element.android.compound.theme.Theme
+
+@Composable
+fun ElementPreviewBlack(
+    showBackground: Boolean = true,
+    content: @Composable () -> Unit
+) {
+    ElementPreview(
+        theme = Theme.Black,
+        showBackground = showBackground,
+        content = content
+    )
+}

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/ElementPreviewDark.kt

@@ -9,6 +9,7 @@
 package io.element.android.libraries.designsystem.preview
 
 import androidx.compose.runtime.Composable
+import io.element.android.compound.theme.Theme
 
 @Composable
 fun ElementPreviewDark(
@@ -16,7 +17,7 @@ fun ElementPreviewDark(
     content: @Composable () -> Unit
 ) {
     ElementPreview(
-        darkTheme = true,
+        theme = Theme.Dark,
         showBackground = showBackground,
         content = content
     )

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/ElementPreviewLight.kt

@@ -9,6 +9,7 @@
 package io.element.android.libraries.designsystem.preview
 
 import androidx.compose.runtime.Composable
+import io.element.android.compound.theme.Theme
 
 @Composable
 fun ElementPreviewLight(
@@ -16,7 +17,7 @@ fun ElementPreviewLight(
     content: @Composable () -> Unit
 ) {
     ElementPreview(
-        darkTheme = false,
+        theme = Theme.Light,
         showBackground = showBackground,
         content = content
     )

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/preview/ElementThemedPreview.kt

@@ -21,6 +21,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.unit.dp
+import io.element.android.compound.theme.Theme
 import io.element.android.libraries.designsystem.utils.CommonDrawables
 
 @Composable
@@ -40,14 +41,14 @@ fun ElementThemedPreview(
         if (vertical) {
             Column {
                 ElementPreview(
-                    darkTheme = false,
+                    theme = Theme.Light,
                     showBackground = showBackground,
                     drawableFallbackForImages = drawableFallbackForImages,
                     content = content,
                 )
                 Spacer(modifier = Modifier.height(4.dp))
                 ElementPreview(
-                    darkTheme = true,
+                    theme = Theme.Dark,
                     showBackground = showBackground,
                     drawableFallbackForImages = drawableFallbackForImages,
                     content = content
@@ -56,14 +57,14 @@ fun ElementThemedPreview(
         } else {
             Row {
                 ElementPreview(
-                    darkTheme = false,
+                    theme = Theme.Light,
                     showBackground = showBackground,
                     drawableFallbackForImages = drawableFallbackForImages,
                     content = content,
                 )
                 Spacer(modifier = Modifier.width(4.dp))
                 ElementPreview(
-                    darkTheme = true,
+                    theme = Theme.Dark,
                     showBackground = showBackground,
                     drawableFallbackForImages = drawableFallbackForImages,
                     content = content

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/theme/ElementThemeApp.kt

@@ -18,7 +18,6 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.staticCompositionLocalOf
 import io.element.android.compound.theme.ElementTheme
 import io.element.android.compound.theme.Theme
-import io.element.android.compound.theme.isDark
 import io.element.android.compound.theme.mapToTheme
 import io.element.android.compound.tokens.generated.SemanticColors
 import io.element.android.libraries.core.meta.BuildMeta
@@ -68,7 +67,7 @@ fun ElementThemeApp(
             when (theme) {
                 Theme.System -> AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
                 Theme.Light -> AppCompatDelegate.MODE_NIGHT_NO
-                Theme.Dark -> AppCompatDelegate.MODE_NIGHT_YES
+                Theme.Dark, Theme.Black -> AppCompatDelegate.MODE_NIGHT_YES
             }
         )
     }
@@ -76,7 +75,7 @@ fun ElementThemeApp(
         LocalBuildMeta provides buildMeta,
     ) {
         ElementTheme(
-            darkTheme = theme.isDark(),
+            theme = theme,
             content = content,
             compoundLight = compoundLight,
             compoundDark = compoundDark,