Create PreviewData with sample of UGC used for preview.

Fix preview issue where username was used for room/avatar name.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/AvatarDataProvider.kt

@@ -8,10 +8,12 @@
 
 package io.element.android.libraries.designsystem.components.avatar
 
+import io.element.android.libraries.designsystem.preview.USER_NAME_ALICE
+
 fun anAvatarData(
-    // Let's the id not start with a 'a'.
+    // Let the id not start with a 'a'.
     id: String = "@id_of_alice:server.org",
-    name: String? = "Alice",
+    name: String? = USER_NAME_ALICE,
     url: String? = null,
     size: AvatarSize = AvatarSize.RoomListItem,
 ) = AvatarData(

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

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2026 Element Creations 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
+
+const val USER_NAME_ALICE = "Alice"
+const val USER_NAME_BOB = "Bob"
+const val USER_NAME_CHARLIE = "Charlie"
+const val USER_NAME_CAROL = "Carol"
+const val USER_NAME_DAVID = "David"
+const val USER_NAME_EVE = "Eve"
+const val USER_NAME_JOHN_DOE = "John Doe"
+const val USER_NAME_JUSTIN = "Justin"
+const val USER_NAME_MALLORY = "Mallory"
+const val USER_NAME_SUSIE = "Susie"
+const val USER_NAME_VICTOR = "Victor"
+const val USER_NAME_WALTER = "Walter"
+
+const val ROOM_NAME = "Room name"
+const val SPACE_NAME = "Space name"
+
+const val LAST_MESSAGE = "Last message"