Fix Storybook theme switching persistence

- Apply theme to both document.documentElement and document.body
- Wrap Story in div with data-theme attribute and background/foreground colors
- Ensures theme persists and doesn't flash back to dark

Author: kylecarbs

.storybook/preview.tsx

@@ -23,13 +23,17 @@ const preview: Preview = {
       const theme = context.globals.theme || "dark";
 
       useEffect(() => {
+        // Apply theme to document root
         document.documentElement.dataset.theme = theme;
+        
+        // Also apply to body to ensure it persists
+        document.body.dataset.theme = theme;
       }, [theme]);
 
       return (
-        <>
+        <div data-theme={theme} style={{ minHeight: "100vh", backgroundColor: "var(--color-background)", color: "var(--color-foreground)" }}>
           <Story />
-        </>
+        </div>
       );
     },
   ],