fix(datatables): the roles drawer's Save button is sized like every other

It was the one `unifiedSize="xs"` (h-5) among the drawer action buttons,
where the convention is `md` (h-8), so it read as a different, lesser
control than the Save it sits beside everywhere else.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S5arH3G2Sa1Qqm32veJQ1n

frontend/src/lib/components/workspaceSettings/DataTablePermissionsButton.svelte

@@ -362,7 +362,7 @@
 		{#snippet actions()}
 			<Button
 				variant="accent"
-				unifiedSize="xs"
+				unifiedSize="md"
 				disabled={!hasUnsavedChanges || loading || !!loadError || !!nameError}
 				loading={saving}
 				on:click={requestPreview}