🤖 fix(storybook): restore dark theme as default

When no mode is explicitly set (e.g., viewing 'Latest' without using
the toolbar), default to dark theme instead of system preference.

This ensures consistent default rendering across all environments.

Author: ethanndickson

.storybook/preview.tsx

@@ -21,8 +21,10 @@ const preview: Preview = {
   decorators: [
     (Story, context) => {
       const mode = context.globals.theme as ThemeMode | undefined;
+      // Default to dark when no mode is explicitly set (e.g., Latest view)
+      const forcedTheme = mode ?? "dark";
       return (
-        <ThemeProvider forcedTheme={mode}>
+        <ThemeProvider forcedTheme={forcedTheme}>
           <Story />
         </ThemeProvider>
       );