Use CircleShape by default on FAB, for coherency with other platforms.

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

@@ -19,6 +19,7 @@ package io.element.android.libraries.designsystem.theme.components
 import androidx.compose.foundation.interaction.MutableInteractionSource
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Close
 import androidx.compose.material3.FloatingActionButtonDefaults
@@ -38,7 +39,7 @@ import io.element.android.libraries.designsystem.preview.PreviewGroup
 fun FloatingActionButton(
     onClick: () -> Unit,
     modifier: Modifier = Modifier,
-    shape: Shape = FloatingActionButtonDefaults.shape,
+    shape: Shape = CircleShape, // FloatingActionButtonDefaults.shape,
     containerColor: Color = FloatingActionButtonDefaults.containerColor,
     contentColor: Color = contentColorFor(containerColor),
     elevation: FloatingActionButtonElevation = FloatingActionButtonDefaults.elevation(),