🤖 fix: clear localStorage theme before Storybook loads

Added preview-head.html to clear the 'uiTheme' from localStorage before
Storybook initializes. This prevents the stored theme from overriding
the Chromatic mode theme that our decorator tries to set.

The flow is now:
1. preview-head.html clears localStorage theme
2. Storybook loads with clean slate
3. Decorator applies theme from context.globals.theme (Chromatic modes)
4. ThemeProvider respects the forcedTheme

This ensures light mode stories render in light and dark in dark.

Author: ethanndickson

.storybook/preview-head.html

@@ -0,0 +1,16 @@
+<script>
+  // This runs BEFORE Storybook and React load
+  // Clear any stored theme so our decorator can set it based on Chromatic modes
+  (function () {
+    const THEME_KEY = "uiTheme";
+    try {
+      // Clear the stored theme - let the decorator handle it
+      window.localStorage.removeItem(THEME_KEY);
+      // Set a neutral initial state
+      document.documentElement.dataset.theme = "dark";
+      document.documentElement.style.colorScheme = "dark";
+    } catch (error) {
+      console.warn("Failed to clear theme in preview-head", error);
+    }
+  })();
+</script>