feat(storybook): replace width with maxWidth for StoryStage

.storybook/StoryStage.svelte

@@ -1,14 +1,18 @@
 <script lang="ts">
 interface Props {
     children: import('svelte').Snippet;
-    width?: string; // Optional width override
+    /**
+     * Tailwind max-width class applied to the card, or 'none' to remove width constraint.
+     * @default 'max-w-3xl'
+     */
+    maxWidth?: string;
 }
 
-let { children, width = 'max-w-3xl' }: Props = $props();
+let { children, maxWidth = 'max-w-3xl' }: Props = $props();
 </script>
 
 <div class="flex min-h-screen w-full items-center justify-center bg-background p-8">
-    <div class="w-full bg-card shadow-lg ring-1 ring-border rounded-xl p-12 {width}">
+    <div class="w-full bg-card shadow-lg ring-1 ring-border rounded-xl p-12 {maxWidth !== 'none' ? maxWidth : ''}">
         <div class="relative flex justify-center items-center text-foreground">
             {@render children()}
         </div>